Drive Application Software Application Set Application Set Title Drive Product File Name for (AS) Date - Revision Position_Follower PowerFlex 700S AS_PF700S_PositionFollower.doc 2/13/03 01 Attention: This document and related file(s) are designed to supplement configuration of the listed drive product. The information provided does not replace the drive products user manual and is intended for qualified personnel only. Description: Position Follower application is designed to “follow” the encoder feedback from another machine section (the master). The speed loop and position loop in the PowerFlex 700S will be used to synchronize the speed feedback encoder of the follower PowerFlex 700S motor to the master encoder. Electronic gearing can be used to match the speed of (2) machines with different gear ratios or electronic gearing can be used to make the (2) machines run at different ratios. Limitations: Requires that the motor on the PowerFlex 700S has an encoder. Options & Notes: Default configuration for 3 wire control through digital inputs may be changed to 2wire control or for operation through 20-COMM-x module. After downloading *.dno file, the Fdbk Config, Pwr Circuit Diag, Direction Test, Motor Tests, and Inertia Measure parts of the Startup routine should be performed to auto-tune the PF700S drive to the motor. Drive Input & Output Connections: Inputs Function DI 1 Start DI 2 Stop DI 3 Jog 1 DI 4 DI 5 DI 6 AI 1 AI 2 AI 3 Encoder 0 (Primary) Encoder 1 (Secondary) Outputs DO 1 DO 2 DO 3 AO 1 AO 2 AO 3 Description Used to independently jog the PF700S follower when the position loop is disabled. NA NA NA NA PF700S Motor Feedback Feedback from master Function NA NA AS_PF700S_PositionFollower.doc Form Revision – A Page 1 of 4 Encoder Input 0 is wired to the quadrature encoder on the PF700S Motor. Encoder Input 1 is wired to the master encoder. Description Drive Application Software Application Set Parameter Configurations Changes from Default Parameter Settings Par Name Value 10 Speed Ref 1 11 Speed Ref 1 Div 17 Jog Speed 1 32 Accel Time 1 33 Decel Time 1 90 Spd Ref BW 151 Logic Command B13 = 1 232 233 Encoder0 PPR Encoder1 PPR per app per app 740 Position Control B01 = 1 742 Posit Ref Sel 743 [Aux Posit Ref] 745 PositRef EGR Mul 746 PositRef EGR Div 753 Posit Offset 1 755 Posit Offset Spd 768 PositRef P Gain 775 Xreg Spd LoLim 776 Xreg Spd HiLim AS_PF700S_PositionFollower.doc Form Revision – A Page 2 of 4 Link 241 1AuxPosit Ref 240 Description Speed feedback from Encdr1 (master) becomes the speed reference for the PF700S. Sets the ratio between the master speed reference and the PF700S follower. See notes on setting the gear ratio and speed reference scaling. Set per application requirements. Set to a value lower than the master accel. Or the speed ramp can be disabled by turning on bit 0 in p151 [Logic Command]. Set to a value lower than the master decel. Or the speed ramp can be disabled by turning on bit 0 in p151 [Logic Command]. Gain of the speed loop. The speed loop should be tuned before enabling the position loop. See tech tip “20D-TT-BasicSpdTune” for tips on tuning the speed loop at the following link: http://www.ab.com/drives/powerflex/pf700s/application _tech/index.html Bit 13 can be turned on/off to enable/disable the position loop. Sets the PPR for the motor feedback. Sets the PPR for the master encoder. Bit 1 is turned on to send the output of the position loop to the speed regulator. Sets the position loop to follow the auxiliary position reference, which in this case will be Encdr1 Position. Encoder counts from Encdr1 (master) becomes the position reference. This sets the multiplier for the position reference electronic gear ratio. The settable range is -1000000 to +1000000. See notes on setting the gear ratio. This sets the divider for the position reference electronic gear ratio. The settable range is 1 to 2000000. See notes on setting the gear ratio. This sets a position offset to advance or retard the follower if necessary. This can be set from a PLC and can be a positive or negative value. See notes on using the position offset. Sets the speed change used to advance or retard the follower when a value set in p753. Set per application requirements. Sets the proportional gain for the position loop. Set to 1/5th (20%) of p90 after tuning the speed loop. Sets the negative speed limit for the output of the position loop. This should be set to the negative value of p753 [Position Offset 1]. Sets the positive speed limit for the output of the position loop. This should be set to the positive value of P753 [Position Offset 1]. Drive Application Software Application Set Par 838 839 Name DigIn1 Sel Dig In2 Sel Value Start Normal Stop 840 Dig In3 Sel Jog 1 Link Description Start input for 3 wire control. Stop input for 3 wire control. Used to independently jog the PF700S follower when the position loop is disabled. Notes for jogging the PowerFlex 700S follower drive independently: When you wish to run the PowerFlex 700S follower drive independently, turn off p151 [Logic Command] bit 13 to disable the position loop and the position loop will stop counting. p151, bit 13 can be controlled from a communication network. Then command Jog 1 through a digital input or communication network. Notes for controlling the position offset of the PowerFlex 700S follower drive: Before advancing or retarding the PowerFlex 700S follower drive, p755 [Posit Offset Spd] needs to be set to a value other than 0. p755 [Posit Offset Spd] sets the speed change used to advance or retard the follower. During the advance or retard operation it is added or subtracted from the speed the follower already running. p755 [Posit Offset Spd] is in units of RPM’s, and is set to a positive value. p755 [Posit Offset Spd] can remain set throughout the PowerFlex 700S follower’s normal operation. To advance or retard the follower using a relative position offset, perform the following steps: 1. Add a value (in counts) in p753 [Posit Offset 1]. For a positive move, add a positive value to p753. For a negative move, add a negative value to p753. For example, with a 1024 ppr encoder, add a value of 4096 to p753 to advance the follower forward one motor revolution. To advance or retard the follower using an absolute position offset, perform the following steps: 1. Set a value (in counts) in p753 [Posit Offset 1]. For a positive move, set p753 to a positive value. For a negative move, set p753 to a negative value. For example, with a 1024 ppr encoder, set p753 to a value of 4096 to move forward one motor revolution. 2. After the move is done, set p740 [Position Control], bit 5 “X Offset Ref” to a 1. 3. Set p753 [Posit Offset 1] = 0. 4. Set p740 [Position Control], bit 5 “X Offset Ref” to a 0. p753 [Posit Offset 1] and p740 [Position Control] can be controlled over a communication network. Notes for setting the gear ratio and speed reference scaling on the PowerFlex 700S follower drive: Example 1: Matching speeds of (2) machines with different gear ratios In this example, the encoders are mounted on the motors. There is a gear box between each motor and each machine. Each gear box has a different ratio. We want to match the speeds on the output side of the gear box (machine side). Here is the given information: PPRm =1024 PPR PPRf = 1024 PPR Inputm : Outputm = 533:236 Inputm : Outputf = 533:163 where PPRm = the PPR of the master encoder PPRf = the PPR of the follower encoder Inputm : Outputm = gear ratio of master gear box (number of input teeth : number of output teeth) Inputf : Outputf = gear ratio for follower gear box (number of input teeth : number of output teeth) p 745 PPR f • Input f •Output m 1024 • 533 • 236 = = p 746 PPR m • Input m •Output f 1024 • 533 • 163 AS_PF700S_PositionFollower.doc Form Revision – A Page 3 of 4 Drive Application Software Application Set Solving for the lowest common denominator, the 1024s on the top and bottom cancel out and the 533s on the top and bottom cancel out so that: p 745 236 = p 746 163 Therefore, P745 [PositRef EGR Mul] = 236 and P745 [PositRef EGR Div] = 163. This will close the position loop and the angular velocities of the master and follower will match exactly. p11 [Speed Ref 1 Div] is calculated: p11 = Input m •Output f Input f •Output m = 533 • 163 = 0.6907 533 • 236 Notice that the encoder PPRs should not be included in the calculation for P11. This parameter is rounded to the 4th decimal place. The position loop gear ratios will be exact, so that the master and follower track exactly. Example 2: Using electronic gearing to make the (2) machines run at different ratios. In this example the encoders are mounted on the motors. The motors are directly coupled to the load and we want the follower to run at 4 times the speed of the master. PPRm =1024 PPR PPRf = 1024 PPR Ratiof : Ratiom = 4:1 where; PPRm = the PPR of the master encoder PPRf = the PPR of the follower encoder Ratiof : Ratiom = the desired ratio between the follower speed and the master speed p 745 PPR f • Ratio f 1024 • 4 = = p 746 PPR m • Ratio m 1024 • 1 Solving for the lowest common denominator, the 1024’s on the top and bottom cancel out so that: p 745 4 = p 746 1 Therefore, P745 [PositRef EGR Mul] = 4 and P745 [PositRef EGR Div] = 1. This will set up the position loop of the follower to move 4 counts for every 1 count of the master. p11 [Speed Ref 1 Div] is calculated: p11 = Ratio m 1 = = 0.25 Ratio f 4 Notice that the encoder PPR’s should not be included in the calculation for p11. This parameter is rounded to the 4th decimal place. The position loop gear ratios will be exact, so that the follower tracks at 4 times the master’s speed. AS_PF700S_PositionFollower.doc Form Revision – A Page 4 of 4