Hi.
I got a task to control couple of danfoss fc202 drives on ABB PM5630 over modbuss.
Question i have is: since i need to read stw, speed, amp, kw and write speed, ctw is it better to just simply cyclically read/write data or just read and if detected change in ctw or speed setpoint do stop and do one write cycle? There are 7 drives/motors in total
Anyone got any experience in codesys with such task?
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HI, i used FC302 and FC280 over modbus RS485
My application was read stw amp alarms and i used a step by step read beacuse only one parameter can be read at a time.
When reading many parameters, the refresh is also several seconds, this is not nice.
The writing of the speed reference was also in the loop and therefore took place with a slow refresh.
But I didn't have to constantly vary the speed.
To control the drives I preferred to use the terminal board, instead of ctw.
I currently use FC VFDs with ethernet/ip and there are no problems with timing.
Last edit: gatto 2022-09-21
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yes i read about parameters being in different registers with empty spaces, so you cant just read area, you need to read one by one. Drives will be used to regulate pressure and air flow by pid, so there will be quite a lot of speed control. Project uses RS485. Will there be much delay?
I was thinking about reading one drive STW,AMPS,KW,SPEED and then just overwrite CTW AND reference even tho its not changed so i would not have to write script to check if speed or CTW is changed
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi.
I got a task to control couple of danfoss fc202 drives on ABB PM5630 over modbuss.
Question i have is: since i need to read stw, speed, amp, kw and write speed, ctw is it better to just simply cyclically read/write data or just read and if detected change in ctw or speed setpoint do stop and do one write cycle? There are 7 drives/motors in total
Anyone got any experience in codesys with such task?
HI, i used FC302 and FC280 over modbus RS485
My application was read stw amp alarms and i used a step by step read beacuse only one parameter can be read at a time.
When reading many parameters, the refresh is also several seconds, this is not nice.
The writing of the speed reference was also in the loop and therefore took place with a slow refresh.
But I didn't have to constantly vary the speed.
To control the drives I preferred to use the terminal board, instead of ctw.
I currently use FC VFDs with ethernet/ip and there are no problems with timing.
Last edit: gatto 2022-09-21
yes i read about parameters being in different registers with empty spaces, so you cant just read area, you need to read one by one. Drives will be used to regulate pressure and air flow by pid, so there will be quite a lot of speed control. Project uses RS485. Will there be much delay?
I was thinking about reading one drive STW,AMPS,KW,SPEED and then just overwrite CTW AND reference even tho its not changed so i would not have to write script to check if speed or CTW is changed
will be on the order of a few seconds
good luck