FPU-16 MODBUS PROTOCOL/DATA LOGGER MANUAL JULY 1997 PRELIMINARY Copyright 1997 by Startco Engineering Ltd. All rights reserved. Publication: FPU-16-MB-M Document: S95-F160-000MB Printed in Canada. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Disclaimer DISCLAIMER This document has been downloaded from the Internet and might not be complete— document quality and formatting depend on the user's computer. This Internet manual is intended as a temporary guide—obtain an original document from Startco or from an authorized Startco distributor. Specifications are subject to change without notice. Startco Engineering Ltd. is not liable for contingent or consequential damages, or for expenses sustained as a result of a malfunction, incorrect application, or incorrect adjustment. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page i TABLE OF CONTENTS PAGE 1. MODBUS PROTOCOL DESCRIPTION ......................................................... 1 2. MODBUS MESSAGE SYNCHRONISATION.................................................. 1 3. ERROR CHECKING ....................................................................................... 2 4. 4.1 4.2 4.3 COMMANDS SUPPORTED ........................................................................... READ REGISTERS AS COILS (CODE 01) .................................................... READ OUTPUT REGISTERS (CODE 03) ...................................................... WRITE TO REGISTER.................................................................................... 4.3.1 MESSAGE FORMAT FOR FUNCTION CODE 06................................ 4.3.2 MESSAGE FORMAT FOR FUNCTION CODE 16................................ EXCEPTION RESPONSES............................................................................. 4.4.1 ILLEGAL ADDRESS (CODE 2)............................................................. 4.4.2 FPU BUSY (CODE 6) ............................................................................ 2 3 3 4 4 5 6 6 6 5. 5.1 FPU SPECIFIC INFORMATION ..................................................................... DATABASES ................................................................................................... 5.1.1 SET POINT MEMORY........................................................................... 5.1.2 DISPLAY MEMORY............................................................................... 5.1.3 RESET MEMORY.................................................................................. 5.1.4 TRIP-STATUS-BIT DEFINITIONS ........................................................ 5.1.5 ALARM-STATUS-BIT DEFINITIONS .................................................... 5.1.6 MOTOR-STATUS DEFINITIONS .......................................................... 6 6 6 7 8 9 9 9 6. 6.1 6.2 6.3 6.4 FPU-16 DATA LOGGING OPTION ................................................................. CONFIGURATION REGISTERS..................................................................... REGISTER DEFINITIONS............................................................................... TRIGGER DEFINITIONS................................................................................. DATA-LOGGING RECORD FORMAT ............................................................ 10 10 10 12 13 7. FPU-16 STATION-ADDRESS SELECTION ................................................... 13 8. CONFIGURATION SWITCHES ...................................................................... 15 9. SPECIFICATIONS ........................................................................................... 15 10. 10.1 10.2 INTERFACE CONVERTER............................................................................. NETWORK INTERCONNECTION .................................................................. RS-485 TERMINATION................................................................................... 16 16 17 4.4 Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page ii FIGURES FIGURE PAGE 1 READ COILS ................................................................................................... 3 2 READ OUTPUT REGISTERS ........................................................................ 4 3 PRESET SINGLE REGISTER USING CODE 06............................................ 5 4 PRESET SINGLE REGISTER USING CODE 16............................................ 5 5 RS-232 TO RS-485 CONVERTER.................................................................. 18 6 FPU-16 DETAILED APPLICATION USING MODBUS PLC ........................... 19 TABLES TABLE PAGE 1 SET POINT MEMORY..................................................................................... 7 2 DISPLAY MEMORY......................................................................................... 8 3 RESET MEMORY............................................................................................ 8 4 TRIP-STATUS BITS ........................................................................................ 9 5 ALARM-STATUS BITS .................................................................................... 9 6 MOTOR-STATUS BITS ................................................................................... 9 7 CONFIGURATION REGISTERS..................................................................... 10 8 DATA LOGGER RECORD FORMAT.............................................................. 13 9 MODE-8 PROGRAM OPTIONS ...................................................................... 14 10 BAUD RATE..................................................................................................... 15 Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 1 FPU-16 MODBUS PROTOCOL 1. MODBUS PROTOCOL DESCRIPTION The FPU-16 implements the Modbus RTU protocol as described in the Gould Modbus Reference Guide, Publication PI-MBUS-300 Rev. B. The communication system consists of a single master and up to 62 FPU-16 slaves. All devices are connected using two-wire RS-485 network hardware. If the master does not have an RS-485 port, a RS-232 to RS-485 converter is required. The converter must have automatic send-data control (SD). SD control does not require hand-shaking lines since it uses the data line to control the transmit/receive line on the RS-485 transceivers. Only the master can initiate a message transaction. Messages can be addressed to individual slaves or they can be broadcast messages. Broadcast messages are executed on the FPU-16 slaves but unlike individually addressed messages, the slaves do not generate a reply message. 2. MODBUS MESSAGE SYNCHRONISATION Message synchronisation is accomplished by detection of an idle communication line. The communication line is considered idle when no communication exists for an equivalent delay of 3.5 characters. The first byte received after idle-line detection is interpreted as the address byte of the next message. Message bytes must be transmitted in a continuous stream until the complete message has been sent. If a delay of more than 3.5 characters exists within the message, the message is discarded. Response messages from the FPU-16 are delayed by at least 3.5 character delays. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual 3. Page 2 ERROR CHECKING Modbus RTU uses a 16-bit cyclic redundancy check (CRC). The error check includes all of the message bytes, starting with the first address byte. The following procedure generates the CRC for a message: CONSTANT = A001 (HEX) CRC_REGISTER = FFFF (HEX) FOR each data_byte in the message: GET data_byte XOR (data_byte, right 8 bits of CRC_REGISTER) DO 8 times SHIFT CRC_REGISTER 1 bit to the right IF bit shifted out was a 1 XOR (CONSTANT, CRC_REGISTER) END IF END DO END FOR The contents of the CRC_REGISTER is appended to the message with the LSB first, followed by the MSB. When a CRC error is detected in the FPU-16, the message is discarded and there will be no response from the FPU-16. If the CRC check is correct but the internal data in the message is not correct, the FPU-16 will respond with one of two exception responses listed in Section 4.4. 4. COMMANDS SUPPORTED The FPU-16 Modus Protocol supports three command messages, Read Coils, Read Output Registers, and Preset Single Register. In the Modbus Protocol, holding resisters are accessed using function code 03 and 06, and start at 40001 decimal. For example, the first holding register in a 584 would be register 40001 and the output register address generated for the message would be 0000. Coils are accessed using function code 1 and are numbered from zero (coil 1 = zero, coil 2 = one, etc.). All FPU-16 data can be accessed using the holding register command codes 03 and 06. Alternately, the holding registers can also be read as 16 bits using the coil-read command code 01. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual 4.1 Page 3 READ REGISTERS AS COILS (CODE 01) Each of the 16 bit registers in the FPU-16 can be read as groups of 16 bits or coils using this command. The first byte of the message is the slave address. The second byte is the function code (01). Bytes three and four specify the starting coil address and the next two bytes specify the number of coils to read. The last two bytes contain the CRC code for the message. The two-byte values of starting coil address and number of coils to read are transmitted with the high-order byte followed by the low-order byte. To read a holding register as 16 coils, you specify the starting register number as the starting coil and request 16 coils. For example, to read the trip status of holding register 40041 in slave #10 as 16 coils, you specify the starting address as 41 and request 16 coils (coils 41 to 56). The FPU-16 responds by sending two bytes of information. These two bytes are interpreted as 2 groups of 8 coils for a total of 16 coils. READ COILS HEX BYTE 0A 01 00 28 00 10 BC B5 DESCRIPTION Slave Address Function Code MSB of First Coil Address LSB of First Coil Address MSB of Number of Coils LSB of Number of Coils LSB of CRC MSB of CRC FIGURE 1 Coils must read in groups of 16 and the starting coil address must be the same as the register address (except the coils start at 0001 instead of 40001). 4.2 READ OUTPUT REGISTERS (CODE 03) Read Output Registers allows the user to obtain information from the FPU-16 in 16-bit format. The first byte of the message is the slave address,. The second byte is the function code (03). Bytes three and four indicate the starting register. The next two bytes specify the number of 16-bit registers to read. The last two bytes contain the CRC code for the message. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 4 The two-byte values of starting register and number of registers to read are transmitted with the high-order byte followed by the low-order byte. The CRC value as calculated in Section 3 is sent with the LSB first followed by the MSB. The following message will obtain the value of register 2 (Modbus 40002) from slave 1. Note that the Modbus registers are numbered from zero (40001 = zero, 40002 = one, etc.). READ OUTPUT REGISTERS HEX BYTE 01 03 00 01 00 01 D5 CA DESCRIPTION Slave Address Function Code MSB Register Address LSB Register Address MSB Number of Registers LSB Number of Registers LSB CRC MSB CRC FIGURE 2 The message length for this message is fixed at 8 bytes. The addressed slave responds with its address and function code (03), followed by the information field. The information field contains an 8-bit byte count and the 16-bit data from the slave. The byte count specifies the number of bytes of data in the information field. The data in the information field consists of 16-bit data arranged so that the MSB is followed by the LSB. 4.3 WRITE TO REGISTER Function code 06 or 16 is used to make set-point changes. The FPU-16 does not allow setting multiple registers so when using function code 16, only one register should be set. 4.3.1 MESSAGE FORMAT FOR FUNCTION CODE 06 The message to the FPU-16 consists of the FPU-16 address followed by the function code 06 and two 16-bit values. The first 16-bit value specifies the internal FPU-16 register to be modified and the second value is the 16-bit data. Provided no errors occurred, the slave will re-send the original message to the master. The response message is returned only after the command has been executed on the FPU-16. This will take approximately 300 ms. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 5 The following message will set register 4 to 300 in slave #5. PRESET SINGLE REGISTER USING CODE 06 HEX BYTE 05 06 00 03 01 2C 78 03 DESCRIPTION Slave Address Function Code MSB Register Address LSB Register Address MSB of Data LSB of Data LSB of CRC MSB of CRC FIGURE 3 4.3.2 MESSAGE FORMAT FOR FUNCTION CODE 16 The FPU-16 supports pre-setting a single register using function code 16. Presetting multiple registers is not supported. Figure 4 shows the message for setting register 4 to 300 in slave #5. PRESET SINGLE REGISTER USING CODE 16 HEX BYTE 05 10 00 03 00 01 02 01 2C 94 EE DESCRIPTION Slave Address Function Code MSB Register Address LSB Register Address MSB of Quantity (Must be 00) LSB of Quantity (Must be 01) Byte Count (Must be 02) MSB of Data LSB of Data LSB CRC MSB CRC FIGURE 4 The FPU-16 will reply with the Slave Address, Function Code, Register Address, and the Quantity followed by the CRC Code for a total of 8 bytes. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual 4.4 Page 6 EXCEPTION RESPONSES The FPU-16 supports two exception responses, Illegal Address and FPU Busy. The exception message consists of the slave address followed by a retransmission of the original function code. The function code will have the most-significant bit set to indicate on error. The 8-bit byte following the function code is the exception response code. The 16-bit CRC is at the end of the message. 4.4.1 ILLEGAL ADDRESS (CODE 2) This error indicates that the register number specified in the data field of the master message is not an allowable register address for the FPU-16. 4.4.2 FPU BUSY (CODE 6) This error occurs when a valid message was received but the FPU-16 was busy processing a long duration program command. The message must be retransmitted at some later time. 5. FPU-SPECIFIC INFORMATION The FPU-16 serial-port data base is updated every 300 ms. Database values can be read one by one or as a group. Since these values are updated every 300 ms, the master need not read these values any faster than 300 ms. In the case of set point-write or reset commands, only one set point or reset command may be processed every 300 ms. Unused registers (0x12 to 0x17) must not be included in read/write instructions. If all information must be retrieved, two instructions are required. One instruction is used for set-point memory and the other is used for display memory. 5.1 DATA BASE 5.1.1 SET POINT MEMORY You can read or write to the set-point memory. Individual or groups of set points can be read; however, set points must be written one at a time and only one set point may be changed every 300 ms. Set-point memory is organised in 16 bit words. Data-base values less than 256 will have 0 stored in the high-order byte. Data-base values are transmitted as two 8-bit bytes, with the high byte transmitted first. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 7 Set-point write instructions must have the data in the 16-bit format. Set-point values greater than the delete value are forced to the appropriate delete value. For set points with no delete value, the maximum value of the range is stored. Set-point values below the minimum are forced to the minimum value. SET POINT MEMORY MODBUS REG. NO. NO. SET POINT (16 BIT) RANGE DELETE INCREMENT 40001 0x00 I²t Trip 1-45 46 1 40002 0x01 I²t Alarm 1-45 46 1 (1) 40003 0x02 Short Time Trip 10-90 91 1 (1) 40004 0x03 Short-Time Alarm 10-90 91 1 (1) 40005 0x04 Instantaneous Trip 10-90 91 1 (1) 40006 0x05 Instantaneous Alarm 10-90 91 1 40007 0x06 Unbalance Trip 5-75 76 1 40008 0x07 Unbalance Alarm 5-75 76 1 40009 0x08 40010 0x09 40011 0x0A Earth-Leakage Trip 1-100 101 1 40012 0x0B Earth-Leakage Alarm 1-100 101 1 40013 0X0C FLA (.45-.93)*CT-Primary Rating 40014 0x0D 40015 0x0E Mode 5 Level 1 0-255 1 40016 0x0F Mode 5 Level 2 0-255 1 40017 0x10 CT-Primary Rating 20-1200 5 40018 0x11 EFCT-Primary Rating 5, 50-2000 50 (1) Set point is 10 times actual value. A value of 15 corresponds to 1.5 X Phase-CT-Primary Rating. TABLE 1 The high-order nibble of Mode 8 level 2 contains the FPU station address. This value cannot be changed via the serial port. 5.1.2 DISPLAY MEMORY Display memory is read-only memory organised in 16 bit words. Display values less than 256 will have 0 stored in the high-order byte. Data-base values are transmitted as two 8-bit bytes, with the high byte transmitted first. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 8 DISPLAY MEMORY MODBUS NO. 40025 40026 40027 40028 40029 40030 40031 40032 40033 40034 40035 40036 40037 40038 40039 40040 (1) REG. NO. 0x18 0x19 0x1A 0x1B 0x1C 0x1D 0x1E 0X1F 0X20 0x21 0x22 0x23 0x24 0x25 0x26 0x27 DESCRIPTION Phase A Current Phase B Current Phase C Current Unbalance (1) Earth Leakage Percent I²t Pre-Trip Phase A Pre-Trip Phase B Pre-Trip Phase C Pre-Trip Unbalance (1) Pre-Trip Earth Leakage Pre-Trip I²t Operation Count Reset Time Spare Station Address of FPU Trip Status Bits 40041 0x28 Alarm Status Bits 40042 0x29 Motor Status Bits 40043 0x2A Divide reading by 10 for actual amperes. Resolution 1/10 A. TABLE 2 5.1.3 RESET MEMORY The memory location 0x0078 (40121) is reserved for the reset function and is a write-only location. The 16-bit data specifies the reset function. A write to register 0x0078 (40121) will perform the function indicated. Only one reset function is processed every 300 ms. RESET MEMORY (2) DATA DESCRIPTION (2) 0000 Null Function Trip Reset 0001 Latches-Alarm Reset 0002 Not Used 0003 Emergency Thermal Reset 0004 Not Used 0005 FbAd Reset 0006 This function accesses the FPU-16 processor but does not perform any function. TABLE 3 Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 9 5.1.4 TRIP-STATUS-BIT DEFINITIONS The trip status bits indicate the FPU-16 trip conditions. TRIP STATUS BITS BIT NUMBER 0 (LSB) 1 2 3 4 5 6 7 TRIP FUNCTION 1 = I²t Trip 1 = Short-Time Trip 1 = Instantaneous Trip 1 = Unbalance Trip 1 = Earth-fault Trip Not Used Not Used 1 = Memory-Fault Trip TABLE 4 5.1.5 ALARM-STATUS-BIT DEFINITIONS The alarm-status bits indicate the FPU-16 alarm conditions. ALARM-STATUS BITS BIT NUMBER 0 (LSB) 1 2 3 4 5 6 7 ALARM FUNCTION 1 = I²t Alarm 1 = Short-Time Alarm 1 = Instantaneous Alarm 1 = Unbalance Alarm 1 = Earth-fault Alarm Not Used Not Used 1 = Memory-Fault Alarm TABLE 5 5.1.6 FPU-16 STATUS DEFINITIONS These bits define the FPU status. MOTOR-STATUS BITS BIT NUMBER 0 (LSB) 1 FUNCTION 1 = Load Current > 10% 1 = Contact Closed, 0 = Contact Open TABLE 6 Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual 6. Page 10 FPU-16 DATA LOGGING OPTION The FPU-16 data logger captures time-stamped meter data using either a time or event trigger mechanism. Captured records are stored in non-volatile memory, which has a data retention of at least 10 years. The real-time clock (RTC) continues to operate even without control voltage. Configuration registers are used to configure the data logger. The same command format as described in section 4 is used for data logger communication. Unlike the set point and reset memory however, the data logger allows for multiple writes to the configuration registers. 6.1 CONFIGURATION REGISTERS Table 7 shows the Modbus and register address location of each configuration register. CONFIGURATION REGISTERS MODBUS ADDRESS 40129 40130 40131 40132 40133 40134 40135 40136 40137 40138 40139 REGISTER ADDRESS 0x80 0x81 0x82 0x83 0x84 0x85 0x86 0x87 0x88 0x89 0x8A DESCRIPTION MSB: N/A LSB: Year MSB: Month LSB: Date MSB: Day LSB: Hour MSB: Minute LSB: Second Sample Interval in Seconds Trigger Duration Count Control Trip Status Trigger Mask Alarm Status Trigger Mask FPU-16 Status Trigger Mask Record Counter (Read Only) TABLE 7 6.2 REGISTER DEFINITIONS 16-bit registers are used to configure the data logger. 40129: (read/write) NOT USED (Bits 8:15) YEAR: YEAR (Bits 0:7) 00 to 99 BCD 40130: (read/write) MONTH (Bits 8:15) MONTH: DATE: DATE (Bits 0:7) 01 to 12 BCD 01 to 31 BCD Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 11 40131: (read/write) DAY (Bits 8:15) DAY: HOUR: HOUR (Bits 0:7) 01 to 07 BCD 00 to 23 BCD 40132: (read/write) MINUTE (Bits 8:15) SECOND (Bits 0:7) MINUTES: 00 to 59 BCD SECONDS: 00 to 59 BCD 40133: (read/write) SAMPLE INTERVAL IN SECONDS (Bits 0:15) SAMPLE INTERVAL: 1 to 65536 Seconds A sample interval of 0 is not valid. 40134: (read/write) POST-TRIGGER DURATION (Bits 0:7) POST-TRIGGER DURATION: 0 to 249 (Valid in Event Mask trigger mode only.). The duration count specifies the number of additional records captured after an event-trigger occurs. The time between records is defined by the sample interval. If a trigger occurs while the duration counter is active, this record will be captured but the duration count will not be initialized. The duration count is initialized only at the occurrence of the first event. 40135: (read/write) CLOCK ENABLE (Bit 4) CLEAR COUNTER (Bit 3) MODE (Bits 0:2) CONTROL REGISTER: MODE: 0: Disable data logging. 1: Set trigger to TIME and start recording. 2: Set trigger to EVENT MASK mode and enable trigger. 3 to 7: Not Used. CLEAR COUNTER: 0: The record counter is not cleared. 1: The record counter is cleared. This bit is cleared by the data logger when the counter has been cleared. CLOCK ENABLE: 0: Clock OSC is turned off. (RTC not running) 1: Clock OSC is on. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 12 40136: (read/write) 16-Bit Trip Status Trigger Mask (Bits 0:15) TRIP STATUS TRIGGER MASK: Bits that are set in the mask register enables triggering for the corresponding trip-status bit. For triggering to occur, the selected trip-status bits must be all zero prior to one of the bits going high. 40137: (read/write) 16-Bit Alarm Status Trigger Mask (Bits 0:15) ALARM STATUS TRIGGER MASK: Bits that are set in the mask register enables triggering for the corresponding alarm-status bit. For triggering to occur, the selected alarm-status bits must be all zero prior to one of the bits going high. 40138: (read/write) 16-Bit FPU-16 Status Trigger Mask (Bits 0:15) FPU-16 STATUS TRIGGER MASK: Bits that are set in the mask register enables triggering for the corresponding FPU-16 status bit. If any of the enabled bits changes state, triggering occurs. 40139: (read only) Record Counter RECORD COUNTER: Counts the number of records captured. This is a read-only location and is cleared by using the control register. 6.3 TRIGGER DESCRIPTION With the trigger mode set to TIME, the data logger stores records at fixed time intervals. The time is defined by SAMPLE INTERVAL. In the TIME mode, any trip, alarm or FPU-16 status that matches the mask bits will also be recorded. TRIGGER DURATION does not apply in TIME mode. When the number of records exceeds 250, new records overwrite old records. With the trigger mode set to EVENT MASK, the data logger will trigger on a specific trip, alarm or FPU-16 status condition. The trigger-mask bits define which trip, alarm or FPU-16 status bits will initiate the trigger. Event mask bit locations correspond to the trip-status, alarm-status, and FPU-16 status bits defined in the communications protocol. To enable triggering on a status bit, the corresponding mask bit is set. All selected bits in the trip or alarm status must be zero to arm the trigger. When any or all of the bits in the trip or alarm status transition from zero to one, the data-logger will be triggered. When triggered, the data logger will store the number of records defined by TRIGGER DURATION with a time interval defined by the sample unit/interval settings. In the case of the FPU-16 status, not all bits have to be zero to arm the trigger. Any bit that changes status will cause a trigger. While in "trigger-duration" mode, event triggering is active, however the duration counter is initialized on the first trigger condition. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual 6.4 Page 13 DATA-LOGGING RECORD FORMAT Up to 250 records are stored in non-volatile memory. These records are read-only and are retrieved by specifying the starting address and length for the record. Each record requires a separate read request. The first record (record 0) is always the latest record, and record 249 is always the last record. Each record consists of the following data (Record 0 addresses shown): DATA LOGGER RECORD FORMAT MODBUS ADDRESS 40193 REGISTER ADDRESS 0xC0 DESCRIPTION MSB: N/A LSB: Year MSB: Month LSB: Date MSB: Day LSB: Hour MSB: Minute LSB: Second Trip Status Alarm Status FPU-16 Status Phase A (A) Phase B (A) Phase C (A) Earth Leakage (x10 A) 2 I t (%) Operations Count Pre-Trip Phase A (A) Pre-Trip Phase B (A) Pre-Trip Phase C (A) Pre-Trip Unbalance (%) Pre-Trip Earth Leakage (x10 A) 2 Pre-trip I t (%) TABLE 8 The starting address for a record is defined by: Modbus Address = 40193 + (Record_Number*24) or Register Address = 0xC0 + (Record_Number*24) Where Record_Number=0 is the latest record. NOTE: The record length is a maximum of 24 words or 48 bytes. 7. FPU-16 STATION-ADDRESS SELECTION The second level of the Mode-5 program option is used to specify the FPU-16 station address. Value digits 2 and 3 indicates a decimal address from 0 to 63. Address 0 is the default value and inhibits serial communication. Value digit 1 indicates the relay-operating mode. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 14 MODE-5 PROGRAM OPTIONS (2nd Level) DEFAULT VALUE . . . . . . . . . . 5000 5000 VALUE DIGIT 1 RELAY OPERATING MODE 0 TRIP-RELAY FAIL SAFE ALARM RELAY-FAIL SAFE 1 TRIP-RELAY FAIL SAFE ALARM-RELAY NON FAIL SAFE 2 TRIP-RELAY NON FAIL SAFE ALARM-RELAY FAIL SAFE 3 TRIP-RELAY NON FAIL SAFE ALARM-RELAY NON FAIL SAFE VALUE DIGITS 2 & 3 0 0 6 . . . . 0 1 3 MPU ADDRESS COMMUNICATIONS INHIBITED FPU 1 . . . . FPU 63 TABLE 9 Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 15 The FPU-16 supports the Modbus Broadcast Address for write commands only. Any FPU-16 that is not inhibited (address not zero) will execute broadcast commands. 8. CONFIGURATION SWITCHES Eight DIP switches are located on the back of the communications card. The DIP switches are accessible through the slot on the back of the FPU-16. When viewed from the rear, SW1 is the right-most switch. A switch is CLOSED when the actuator is up (toward the PCB) and OPEN when the actuator is down (away from the PCB). Switches 1 to 3 are used to select the communication baud rate. BAUD RATE BAUD SW1 SW2 SW3 SW4 - SW8 9600 OPEN CLOSED OPEN (DEFAULT) NOT USED 4800 CLOSED CLOSED OPEN 2400 OPEN OPEN CLOSED 1200 CLOSED OPEN CLOSED 600 OPEN CLOSED CLOSED 300 CLOSED CLOSED CLOSED NOTE: SW6 is used for software-update programming and MUST be in the OPEN position for normal communications. SW4, SW5, SW7, and SW8 are not used. TABLE 10 The FPU-16 RS-485 port is fixed at 8 data bits, 1 stop bit, and no parity. 9. SPECIFICATIONS Interface ................................................... Isolated RS-485, 2 wire multi-drop, half duplex. Protocol .................................................... Modbus RTU Baud Rate ................................................ 300 to 9600 Baud. Bit Format................................................. 8 bits, no parity, one stop bit.* Number of FPU’s Connected................... Maximum of 31 units.} Line length................................................ 1200 meters total. Isolation Voltage....................................... 300 Vac continuous Dielectric................................................... 1500 Vac * Terminal 23 (-) is negative with respect to terminal 24 (+) for a binary 1 (MARK or OFF) state. Terminal 23 (-) is positive with respect to terminal 24 (+) for a binary 0 (SPACE or ON) state. } Can be expanded to 62 units with repeater connection. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual 10. Page 16 INTERFACE CONVERTER A communication master with a RS-232 port requires an RS-232 to RS-485 converter. Two types of converters are available and converter selection depends upon the hardware/software configuration of the master. The first type uses hardware control where the RTS line of the RS-232 is used to control the transmit and receive mode of the RS-485 transceiver. When the RTS line is high, the transmitter is enabled and when it is low, the transmitter is disabled and the receiver is enabled. Usually the master software must be specifically designed for use with this type of control. This type of converter is the most common type; however, most software packages do not support the hardware handshaking control. The second type is the "data only" converter. This converter monitors the data from the master and sets the transmitter ON or OFF based on activity on the line. This type of converter requires time to switch from transmit to receive mode. To avoid RS-485 data collision, a reply or turn-around delay is required at the slave. This type of converter will work with all software packages that support a master/slave, half-duplex protocol. The recommended converter is the Model 485COSR or 485CSP manufactured by B&B Electronics, and are available from Startco Engineering Ltd. These converters are "data-only" converters and are configured for operation at 9600 baud. Slower rates require modification to the converter. Consult the factory for operation below 9600 baud. 10.1 NETWORK INTERCONNECTION A general diagram is shown in Figure 6 with more detailed wiring diagrams shown in Figures 4 and 5. FPU-16 communication ports are interconnected using a two-wire twisted pair cable. Communication ports are connected in a daisy-chain method. All FPU-16 + terminals are connected to the white wire, and all FPU-16 - terminals to the black wire. In the case of the 485CSP, the + terminal is connected too the (B) terminal and the - terminal to the (A) terminal. The Model 485COSR and 485CSP are provided with a DB25 connector on the RS-232 side and a terminal block for the RS-485 side. The RS-232 connector is the same for both the 485CSP and 485COSR and is a female connector with the following pins supported. Pin # 1 2 3 7 Description Shield ground Data to converter from computer Data from converter to computer Signal ground Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 17 The RS-485 connector is a terminal block with the following designations: 485CSP ADAPTER DESCRIPTION FR Shield Ground TDA RS485 (-) TDB RS485 (+) RDA RS485 (-) RDB RS485 (+) Signal Ground Remote Power (+) 12 V Remote Power (-) GND 485COSR ADAPTER DESCRIPTION + (RS485 Positive) - (RS485 Negative) If the converter is at one end of the network, a 150 ohm termination is connected between (-) and (+) on this connector. Power for the converter is supplied by an "adapter-type" power supply (Model 485PS) which connects to the + and - terminals of the terminal block. 10.2 RS-485 TERMINATION Termination resistors are required for line lengths greater than 25 meters. Termination resistors are normally selected to match the characteristic impedance of the communication line, and are installed at each end of the network. When the RS-485 line is idle, all of the RS-485 devices are in a receive state. Since the line is not driven, the voltage across the twisted-pair cable is zero. This results in an unknown output state on the master's RS-485 converter which can cause communication problems with the master software. To force the RS-485 line to a known state, each FPU-16 has a 100K pull-up resistor connected from the internal 5-volt supply to the (+) line and a 100K pulldown resistor connected from the (-) terminal to internal circuit ground. The combination of the pull-up, pull-down, and termination resistances results in a voltage on the RS-485 line that must be greater than the 200 mV threshold of the RS-485 receiver to guarantee a valid idle state. For the RS-485 network used with the FPU-16, the termination consists of a 150 ohm resistor in series with a 0.1 mf capacitor. This combination satisfies the valid idle-state requirements and provides the 150 ohm termination for the cable. Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 18 4-40 SCREW C/W RETAINER - + S H RS-232 485C0SR RS-485 6 1 DB25 FEMALE TxD 2 GND 7 2 TxD (-) 2 3 RxD (-) 3 SCREW TERMINAL 2 RS485 (-) 4 SE-TA485 6 RS-232 TO RS-485 CONVERTER RxD 3 DB25 FEMALE DB25 MALE 14 TxD (+) 14 16 RxD (+) 16 3 1 1 1 SH SH 5 7 GND SH 1 RS485 (+) NC 25 + REMOTE POWER TERMINAL ADAPTER 12 - RS-232 TO RS-485 CONVERTER FIGURE 5 Pub. FPU-16-MB-M, July 1997, Preliminary Downloaded from the Internet, see Disclaimer. Pub. FPU-16-MB-M, July 1997, Preliminary RS-232 4 SE-485 COMMUNICATION PACKAGE FOR USE WITH MPU-16A INCLUDES 485CSP, DC POWER PACK AND (2) SE-TA485 JUMPERS ON 485CSP ARE FACTORY INSTALLED USE SHIELDED CABLE AND TERMINATION ASSEMBLY SE-TA485 FOR CABLE LENGTHS OVER 50 FEET (15 METERS) 1. 3. 4. DC POWER PACK RD(B) RD(A) TD(B) TD(A) 2. SE-485 SEE NOTE 2 (485CSP) RS-485 ADAPTER CABLE PART NUMBER: MPU-16A-BM85-RS232 NOTES: 25 PIN 9 PIN 3 Rx 7 GND 1 SHLD 2 Tx SHLD 1 Tx 2 Rx 3 DTR 4 GND 5 DSR 6 RTS 7 CTS 8 9 RS-232 RS-232 3 RS-232 2 RS-232 1 MODBUS BM85 GND OFF CONTROL ECH0 RTS SD ON +12VDC RD(B) TD(B) RD(A) TD(A) FR. GND SHLD SE-TA485 NOTE 3 BLK WHT SE-TA485 9 PIN MALE TO 25 PIN MALE ADAPTER CABLE SEE NOTE 1 23 24 23 24 23 24 23 24 SHIELD UNIT 1 SHIELD UNIT 2 UNIT 3 UNIT 4 SHIELD + - SEE NOTE 4 SHIELD + - SEE NOTE 4 + - SEE NOTE 4 + SEE NOTE 4 ICT-2 ICT-2 ICT-2 ICT-2 Startco Engineering Ltd. FPU-16 Modbus Protocol/Data Logger Manual Page 19 DETAILED APPLICATION USING MODBUS PLC FIGURE 6 Downloaded from the Internet, see Disclaimer.