Technical Note #614 VT-MODEM Interfaces with the PLCDirect DL250 PLC Abstract: This document explains the procedure for interfacing a SIXNET Industrial Telephone Modem with a PLCDirect DL250 PLC. This setup will allow a remote computer to access the serial port on a DL250 PLC via a telephone modem connection. This telephone modem interface provides long distance communications between the operator and the PLC. Diagnostics and troubleshooting can now be done from hundreds of miles away. This saves time and money because problems can be corrected or configuration changes made without traveling to the PLC. Hardware and Software Used: • • • • • • SIXNET Industrial Modem (Part Number: VT-MODEM-1) Serial cable (Part Number: VT-CABLE-MDM which is supplied with theVT-MODEM-1) Serial Cable (Custom made RS-232C DB9M to HD15M) PLCDirect 250 PLC (using Port 2, RS-232C) PLCDirect DirectSOFT Software, V2.3 Analog telephone line connections at both ends Sending and Receiving Modem (SIXNET VT-MODEM-1) Setup Procedure: 1. Use Window’s HyperTerminal to communicate to the modem. Settings can be changed by connecting* the straight through cable, which comes as part of the Industrial Modem package (VTCABLE-MDM) to the serial port on the modem and the serial port of the computer (i.e. serial port COM1, 2 etc.). Note: a) For information on how to use HyperTerminal, please consult the SIXNET VT-MODEM online help guide located on the SIXNET CD in the Product Catalog. b) * Cycle power on your modem each time a cable is disconnected and then reconnected. 2. Start Hyper Terminal. Enter a name for your connection. Select OK. SIXNET • Box 767 • Clifton Park, NY 12065 USA • +1 (518) 877-5173 • FAX +1 (518) 877-8346 • [email protected] TN614.DOC PAGE 1 REV.1.10 MAR 1999 3. Choose the Com port you want to use. Select OK. 4. Enter the appropriate Com properties. Select OK. — Important — Choose the baud rate that matches the PLC or other device that will be connected to the modem. Anytime a setting is saved using &W0 or &W1, the RS232 communication properties are memorized by the VT-MODEM. The saved communication properties will be used for future communications with any attached device that does not initiate communications with the modem (such as most PLC’s). SIXNET • Box 767 • Clifton Park, NY 12065 USA • +1 (518) 877-5173 • FAX +1 (518) 877-8346 • [email protected] TN614.DOC PAGE 2 REV.1.10 MAR 1999 1. The Hyper Terminal screen, on the next page, will appear. To check communication, type AT <Enter>. OK should appear. Send the following AT commands. The commands in bold need to be sent, the others may be necessary if you find you cannot communicate, or have unreliable communications, with the PLC. AT&F&W0&W1<Enter> - Sets the modem to factory defaults ATS0=1<Enter> - Set the modem to auto-answer AT&K0<Enter> - Disables flow control AT&D0<Enter> - Tells the modem to ignore DTR AT%C0<Enter> - Disables data compression AT&V<Enter> - Use this to verify changes ATS37=9<Enter> - Sets the modem to modem baud rate to 9600 ATN0<Enter> - Forces modem to communicate to modem at baud rate set up by S37 AT\N1<Enter> - Sets the operating mode of the modem to direct async.communication, no send/receive buffers, and no error checking AT%E0<Enter> - Disables the internal line quality check 2. Store the above AT commands to user profile 0 (or 1), with the following command: AT&W0 <enter>(or W1). 3. If you wish to load this profile upon power up, you will want to use the load command: AT&Y0 <enter> (or Y1) depending upon which stored profile you saved the previous set of commands to. SIXNET • Box 767 • Clifton Park, NY 12065 USA • +1 (518) 877-5173 • FAX +1 (518) 877-8346 • [email protected] TN614.DOC PAGE 3 REV.1.10 MAR 1999 4. The “receiving” VT-MODEM set-up is complete 5. Repeat steps 1 through 4 for the “sending” VT-MODEM. 6. Connect* your computer to the “sending” VT-MODEM, using the VT-CABLE-MDM. This is a standard straight-through cable with a DB-9(M) connection to the modem and a DB-9(F) connection to the computer. 7. Connect* the DL250 PLC to the “receiving” VT-MODEM, using a cable with the following connectors and wiring: VT-MODEM DL250 PLC DB-9(M) HD-15(M), Port 2 RXD 2 3 /RXD2 (RS-232C) TXD 3 2 /TXD2 (RS-232C) GND 5 7 0V 4 RTS2 (RS-232C)** 5 CTS2 (RS-232C)** * Cycle power on your modem each time a cable is disconnected and then reconnected. ** On the HD-15 jump 4 to 5. SIXNET • Box 767 • Clifton Park, NY 12065 USA • +1 (518) 877-5173 • FAX +1 (518) 877-8346 • [email protected] TN614.DOC PAGE 4 REV.1.10 MAR 1999 8. Call the “receiving” modem. To dial a number in HyperTerminal, you can use the command: ATDT<phone number>. When you have successfully connected to another modem, it will show the baud rate at which you are connected. 9. Exit Hyper Terminal. Select Yes. The modems should not disconnect. 10. Save your session. Select Yes. SIXNET • Box 767 • Clifton Park, NY 12065 USA • +1 (518) 877-5173 • FAX +1 (518) 877-8346 • [email protected] TN614.DOC PAGE 5 REV.1.10 MAR 1999 11. Start the DirectSOFT program. 12. Select new link, which starts the LinkWizard. Select the appropriate communications port. 13. Select 105/205/350/405 Family. SIXNET • Box 767 • Clifton Park, NY 12065 USA • +1 (518) 877-5173 • FAX +1 (518) 877-8346 • [email protected] TN614.DOC PAGE 6 REV.1.10 MAR 1999 14. Select DirectNET serial communication protocol. 15. Name your Link. Select Finish. Link settings are complete. 16. You are now connected to the PLC through the modems. SIXNET • Box 767 • Clifton Park, NY 12065 USA • +1 (518) 877-5173 • FAX +1 (518) 877-8346 • [email protected] TN614.DOC PAGE 7 REV.1.10 MAR 1999 17. When you have completed your tasks within DirectSOFT, exit as usual. 18. Start Hyper Terminal. Re-open the session you saved earlier. 19. Entering the escape sequence +++ will switch the modem from on-line state to command state. The default escape sequence is three successive plus signs not preceded by the AT prefix and not followed by a carriage return. The escape sequence will not be echoed to the screen. The modem will respond SIXNET • Box 767 • Clifton Park, NY 12065 USA • +1 (518) 877-5173 • FAX +1 (518) 877-8346 • [email protected] TN614.DOC PAGE 8 REV.1.10 MAR 1999 to the escape sequence with the OK result code at which point AT commands can be entered. (If you want to return to the on-line state, enter the ATO <enter>command). Enter ATH <enter> to hang-up the connection. Your phone line is now on-hook. VT-MODEM Default LED Indications LED Default Indication Carrier Detect ON when a phone line connection has been established. Data Terminal Ready ON at all times. Receive Data ON when characters are being received through the phone line. Transmit Data ON when characters are being sent from the PLC or attached device. Power LED ON when power is applied to the modem. For additional help, refer to the VT-MODEM online manual, which can be found on the SIXNET CD or downloaded from our Web site at: www.sixnetio.com. SIXNET • Box 767 • Clifton Park, NY 12065 USA • +1 (518) 877-5173 • FAX +1 (518) 877-8346 • [email protected] TN614.DOC PAGE 9 REV.1.10 MAR 1999