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from the automator department...
Prosafe-RS PID Block
PLCs topic
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Posted by shoaib on 1 April, 2008 - 12:08 am
Yokogawa Prosafe-RS does not have PID block. I want to make PID block in Prosafe-RS using ST language. If anybody knows the syntax or code kindly help me out. I need it badly. Thanks.

Posted by a on 1 April, 2008 - 11:04 pm
I think It may not have as ESD PLC generally do not come with PID blocks they will be given only sequential control. PID control should be done through DCS as it is an regulatory control. I have seen same in Triconex PLC.

Optional PID blocks can be there if it is not used as ESD shut down system. This is my understanding.

Posted by shoaib on 3 April, 2008 - 12:42 am
Yes, I understand your point. Bascially we were using separate PID controller for well choke valve rather than DCS because we want local control of PID, but know we want to exclude it from our logic and want only to use Prosafe-RS. Yes, these loops were not sil3. Does anyone know the ST code for making simple PID or even PI block?

Posted by shoaib on 6 April, 2008 - 2:08 pm
plz guys if some body has ST code for PID block please send me the link or code.

Posted by john on 1 May, 2008 - 12:53 am
There is no way to implement PID because of hardware and software limitations. There is no Ao for hardware. I do not recommend using complex calculations on Prosafe-RS.

So you have to create PID block at cs3000 and control by Prosafe-RS.

Posted by Shahid Waqas on 3 May, 2008 - 4:15 am
Prosafe-RS actually has AO hardware.

Posted by shoaib on 14 May, 2008 - 11:43 pm
Yeah, Prosafe-RS has AO but certainly not for PID loop. I have checked, no safety system has a PID loop because it is against the IEC rules to use processor time for control loops in safety system where response time of hazard event is very important.

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