adccommunitymod (AutomationDirect) asked a question.
Created Date: April 13,2016
Created By: slb9
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We build 3- & 4-zone IR conveyor belt furnaces with a CLICK PLC talking to SOLOs being used as temperature controllers (1 SOLO per zone). We have used RS-485 based Modbus RTU serial comms to allow the CLICK and SOLOs talk to each other since 2013 and all has been smooth. The SOLOs perform PID thermal control and send alarms to the CLICK; the CLICK runs our electromechanical panel HMI and does closed loop belt speed control. Now I want to add the capability for a customer to store/retrieve SOLO process recipes to/from CLICK memory, but I ran into a problem with storing/retrieving all 4 groups (groups 0-3) of PID parameter data. When I asked AD tech support the question, I received this reply: "In regards to loading PID Group data to a SOLO over Modbus, the Product Engineer wasn't certain this would work, since it's far outside the intended use/operation of the SOLO. " Any of you SOLO experts out there have any ideas about how to do this?
Created Date: April 14,2016
Created by: Ridgeline Mach
Looking at the manual for Modbus communication, it appears you can read/write to all the variables except Process Value. It just appears doable, but I have zero experience with Solo.
-Todd
Created Date: April 14,2016
Created by: techme
You can write to any Modbus address that is R/W. According to the manual you can write to the PID Group to choose the group and then write to the parameters in that group which are R/W. For instance you can choose Group 0 by writing to the Modbus 44125 address and then read or write a value from or to the Prop, Int, and Der gains ( Modbus address 44106, 44107, & 44108). I tested this and it works. Not sure what you are wanting to write to with your recipe, but the parameters associated with a PID group do work.
Created Date: April 15,2016
Created by: OpZed
Are you trying to read/write all 4 groups at the same time? Solo has packet size restrictions.
http://www.automationdirect.com/static/manuals/solocontrolm/ch7.pdf
Page 7-2:
Data Registers
03: Read Holding Registers (maximum limit is read of eight registers)
06: Write Single Register
16: Write Multiple Registers (maximum limit is eight)
Created Date: April 16,2016
Created by: slb9
Thanks for responding, Todd. You are correct that is all readable/writable -- that has been my experience, too. The SOLO allows you to select 1 of 4 possible sets of PID loop parameters either directly by Group Parameter (0-3) or by Group Parameter 4, which automatically selects the set of PID loop parameters based on the SOLO's measured process temperature proximity to a "target setpoint temperature " value set in each Group Parameter. I was unsure if I could use the Group Parameter # as an index to store the various PID settings for each Group. You can see what Tech Support told me in my original post -- they were unsure.
techme's answer has told me what I needed to know. Good to know you tried it and confirmed that it worked. You da MAN!
Created Date: April 16,2016
Created by: slb9
Thanks for pointing that out, OpZed. No, all our register reads/writes are 1 register at a time. IIRC we read 6 bits at a time once per second when checking our SOLOs for alarm status. We keep our RS-485 Modbus comms at 9600 baud for reliability.
Created Date: April 16,2016
Created by: slb9
tecme-Thanks! "I tested this and it works. Not sure what you are wanting to write to with your recipe, but the parameters associated with a PID group do work. " -- Those words are music to my ears!
As I read the SOLO manual I figured it might work that way, but having you say you 've tried it and it works sure made my day.
I expect to get a chance to test this on our next IR lamp furnace order. I will forward this to the SOLO Product Manager and the AD tech support folks.
Created Date: April 13,2016
Created by: slb9
We build 3- & 4-zone IR conveyor belt furnaces with a CLICK PLC talking to SOLOs being used as temperature controllers (1 SOLO per zone). We have used RS-485 based Modbus RTU serial comms to allow the CLICK and SOLOs talk to each other since 2013 and all has been smooth. The SOLOs perform PID thermal control and send alarms to the CLICK; the CLICK runs our electromechanical panel HMI and does closed loop belt speed control.
Now I want to add the capability for a customer to store/retrieve SOLO process recipes to/from CLICK memory, but I ran into a problem with storing/retrieving all 4 groups (groups 0-3) of PID parameter data. When I asked AD tech support the question, I received this reply:
"In regards to loading PID Group data to a SOLO over Modbus, the Product Engineer wasn't certain this would work, since it's far outside the intended use/operation of the SOLO. "
Any of you SOLO experts out there have any ideas about how to do this?