avlgeneral
Member
Hi guys,
Using connected components workbench with a micro 850 PLC, with expansion AI and AO cards.
Programming a temperature control package for a generator. Consisting of Intake louvers, discharge louvers, re-circulation louvers and a fan with a VFD. It's a basic set up, when its cold the intake and discharge is closed, while the re-circulation opens and the fan runs until its warm enough, then the intake and discharge louvers modulate (through a PID function block) according to temperature.
Just a few questions, due to my poor programming experience.
- I’ve been requested to put a “feedback timeout” block into my code. This is for the louvers, so for example, if the PID output was to request 25% and the louver feedback did not read that in a set amount of time (say, a minute or so) it would output an alarm (I’ve got a warning light). Currently I’ve got a <> function block (not equal too), the 2 variables being the output AO from the PLC and the AI feedback from the louver (if AI does not equal requested AO, alarm), how do I put a deadband in this? My worry is if the output is 8.01V and the feedback is not exactly 8.01V but 8.02V it will cause an alarm.
- Customer has requested that intake louvers never be closed so they don't "suffocate" the generator when its running, and be open a minimum of 25% (this will be an output of 8V from the PLC, as it is an open spring return actuator, this means 2V 0% Closed, 100% open. And 8V 75% closed, 25% open.) What is the best way to go about this? I have set a high clamp of 8V output on the set up of the channel (when enabling channel, adding cards etc.) As it will be controlled from a PID function block. This should never output more than 8V, thus never completely closing the louvers, is this correct?
Thanks
Using connected components workbench with a micro 850 PLC, with expansion AI and AO cards.
Programming a temperature control package for a generator. Consisting of Intake louvers, discharge louvers, re-circulation louvers and a fan with a VFD. It's a basic set up, when its cold the intake and discharge is closed, while the re-circulation opens and the fan runs until its warm enough, then the intake and discharge louvers modulate (through a PID function block) according to temperature.
Just a few questions, due to my poor programming experience.
- I’ve been requested to put a “feedback timeout” block into my code. This is for the louvers, so for example, if the PID output was to request 25% and the louver feedback did not read that in a set amount of time (say, a minute or so) it would output an alarm (I’ve got a warning light). Currently I’ve got a <> function block (not equal too), the 2 variables being the output AO from the PLC and the AI feedback from the louver (if AI does not equal requested AO, alarm), how do I put a deadband in this? My worry is if the output is 8.01V and the feedback is not exactly 8.01V but 8.02V it will cause an alarm.
- Customer has requested that intake louvers never be closed so they don't "suffocate" the generator when its running, and be open a minimum of 25% (this will be an output of 8V from the PLC, as it is an open spring return actuator, this means 2V 0% Closed, 100% open. And 8V 75% closed, 25% open.) What is the best way to go about this? I have set a high clamp of 8V output on the set up of the channel (when enabling channel, adding cards etc.) As it will be controlled from a PID function block. This should never output more than 8V, thus never completely closing the louvers, is this correct?
Thanks
