adccommunitymod (AutomationDirect) asked a question.
Created Date: March 18,2015
Created By: Haus1
**** This post has been imported from our legacy forum. Information in this post may be outdated and links contained in the post may no longer work.****
Hi everyone, I am new to this site and have minimal experience writing anything other than basic ladder (so go easy on me). Anyhow, I am working with a Click PLC, a GS2 VFD, and a C-more micro HMI. I am writing to Modbus addresses 42331-42333 as well as reading from Modbus addresses 48451-48460 in the GS2 drive, ...but are having some issues. I wrote my read/write instruction using bit SC5 (_100ms_Clock) to trigger the first write command, then used the "success " bit from that write instruction to trigger the next read/write instruction, in a cascading fashion, until all read/writes were complete. The read/write works, BUT it's over writing the STOP command from the drives physical "STOP|RESET " button. Something tells me that this is not the most efficient way to do this and are looking for some assistance/pointers. Do I need to interlock the send and receive commands? Do I read/write instructions constantly or only when necessary? I would appreciate any pointers the community may be able to give me.
Created Date: March 18,2015
Created by: Do-more PE
Do I need to interlock the send and receive commands?
Yes
Do I read/write instructions constantly or only when necessary?
Up to you, but writes typically should only happen when something changes.
Created Date: March 18,2015
Created by: scott.lawrence
Do I read/write instructions constantly or only when necessary?
read at timed intervals to keep the PLC updated with the drive status, write when you need to change the status
Created Date: March 18,2015
Created by: Haus1
read at timed intervals to keep the PLC updated with the drive status, write when you need to change the status
OK. So I need to interlock the send/receive, send only when there is a change to be written to the drive, and read at timed intervals. But what about the method I was using to read/write? Is there a way to read a block of sequential addresses simultaneously, or is my "cascading " method ok? Is a read every 100ms adequate? Again, I am very new to this, so I want to understand best practices vs just making it work with my sloppy instructions.
Thanks for all the help. :)
Created Date: March 18,2015
Created by: scott.lawrence
while not in the GS2 manual, the GS1 manual has a section for modbus w/ a CLICK that shows all needed interlocking... it starts on pg 5-20
http://www.automationdirect.com/static/manuals/gs1m/ch5.pdf
Created Date: March 18,2015
Created by: Haus1
while not in the GS2 manual, the GS1 manual has a section for modbus w/ a CLICK that shows all needed interlocking... it starts on pg 5-20
http://www.automationdirect.com/static/manuals/gs1m/ch5.pdf
Thank you very much! This is exactly what I was looking for.
Created Date: March 18,2015
Created by: Haus1
Hi everyone,
I am new to this site and have minimal experience writing anything other than basic ladder (so go easy on me). Anyhow, I am working with a Click PLC, a GS2 VFD, and a C-more micro HMI. I am writing to Modbus addresses 42331-42333 as well as reading from Modbus addresses 48451-48460 in the GS2 drive, ...but are having some issues.
I wrote my read/write instruction using bit SC5 (_100ms_Clock) to trigger the first write command, then used the "success " bit from that write instruction to trigger the next read/write instruction, in a cascading fashion, until all read/writes were complete.
The read/write works, BUT it's over writing the STOP command from the drives physical "STOP|RESET " button. Something tells me that this is not the most efficient way to do this and are looking for some assistance/pointers.
Do I need to interlock the send and receive commands?
Do I read/write instructions constantly or only when necessary?
I would appreciate any pointers the community may be able to give me.