BR

Multiple encoders to CP1L-60DT-A

8 posts in this topic

I need to add 3 encoders to my project. Currently my PLC Inputs are full. I am using high speed counters 0.00 and 0.001 to monitor a motor RPM with an encoder. I now wish to add 3 encoders to monitor position of (3) other linear axis controlled by stand alone (Zeta 6104) stepper drives. I have 3 open outputs on this PLC but all inputs are used. What are my hardware options to add additional encoders to allow me to track and correct the 3 additional axis.

My first thought was to add another CP1L and use PLC1 0.00, 001 for ENC1, PLC1 0.002, 0.003 for ENC2, PLC2 0.00, 001 for ENC3, PLC2 0.002, 0.003 for ENC4. I thought this would allow me to use additional I/O from the second PLC but I am not sure if this is even possible. Is it possible to connect 2 PLCs this way? I will need additional I/O to send to these stepper drives to make the corrections.

Do I need to add an expansion unit to the existing PLC and 2 additional high speed counter modules? The encoders are all Omron E6C2-CWZ6C. I would appreciate any advise on options to add these encoders and help point me in the right direction.

Thanks in advance to any help.

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First of all, the type number of the PLC you mention is not complete (or Omron is using different  type numbers in North America and Europe?). There are no expansion units for the CP1 PLC's that can handle encoders. So a second PLC would be an option. You can connect them through the serial ports or ethernet ports (option boards). But the encoder values exchange will be slow. So controlling the stepper drives should be programmed in each PLC separately.

Another option would be remote I/O to hook up the encoders. But that will require more programming. The remote I/O can be connected to the PLC through any option board for serial or ethernet communication.

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Posted (edited)

Sorry the Plc is a CP1L-M60DT-A. I don't mind the extra programming it is the hardware cost I wish to keep to a minimum. My steppers would need to be placed in a jog mode and run until my encoder values are met so handling that through 2 different pics shouldn't be a problem. I am just not sure of the best way to do the communication of the added plc to the main plc. The current plc would handle the servo and the single step motor axis as well as command the 2nd plc to handle the move on the other 2 stepper axis. The application requires the 3 step drives to be located at the same distance from their homed position. This distance is critical but is never a known position. I am running the 2 steppers in a following mode to the master axis. My thought is in my programming read the encoders at the time the drives are killed and reposition the 3 drives to average position of each encoder position. Hope that makes sense. Feasible?

Edited by BR

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The CP1L-M60DT-A has 4 High Speed Counter inputs. If I counted correctly you need 4 encoders total, correct?

The HSC inputs that are currently occupied with standard inputs can be moved to an expansion card. CP1W-8ED.

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Posted (edited)

Yes I am currently using the HSC on the CP1L-M60DT-A. I am considering placing a serial connection between it and a CP1L-L10 moving the occupied HSC inputs over to it. Use the HSC on the M60 for encoder 1 and the other 2 encoders to the L10. Speed is not an issue as I am correcting a position after a stall detect on the master step motor. I just need to adjust each axis using a jog command to place each axis at the same position independent of each other. I am pretty sure the PLC is able to calculate the average of the 3 encoders and allow me to move each axis to a corrected position. I may have to move each axis or 1 or 2. I won't know until i get feedback from all 3 axis at stall.

Edited by BR

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You could use 1:1 Serial Links between two CP1L PLC's to exchange data. Each PLC will need a CP1W-CIF01 RS-
232C Option Board.

However the CP1L-L10 does not accept this board. You would need a minimum of the CP1L-L14.

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Yes I just seen that I need at least a CP1L-L14 with the additional inputs to do what I need. I figure I will use the L20 allowing me extra I/O if I miss something.

I understand that I will need to use the Link area CIO 3000 to CIO 3015 to communicate between the 2. This will be my first time linking 2 plcs together and programming is a little fuzzy at this time. As I understand it the 1:1 Link area master PLC writes to 3000-3007 the Slave reads this and writes to 3008-3015 which is in tern read by the Master PLC. Is that basically it?

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1:1 Links is a quick and simple to use.

You set one as a Master and the other a Slave in the PLC settings. Download setting to each PLC and BE SURE TO POWER CYCLE for new settings to take effect.

8 words CIO 3000-3007 from the Master PLC are continuously written to CIO 3000-3007 in the Slave PLC.

Likewise 8 words CIO 3008-3015 from the Slave PLC are continuously written to CIO 3008-3015 in the Master PLC.

ONLY WRITE DATA TO CIO 3000-3007 in the Master and CIO 3008-3015 in the Slave.

ONLY READ DATA FROM  CIO 3008-3015 in the Master and CIO 3000-3007 in the Slave.

And you should be good to go.

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