Iandayen
Member
I have a program I need to work out for a client and I'm having trouble figuring out the correct logic to do it. Let me see if I can explain it properly.
Programming done in Studio 5000 - compactlogix processor.
There are some Supply and Exhaust fans I need to control (4 of each) to keep a room temperature around 90 degrees. They have 4 combinations of fans they want to run depending on temperature. I'm calling these F1 through F4. Fans are all on or off, no speed control, just a digital output to a motor starter in MCC.
F1 Active below 85 Degrees
F2 Active above 90 Degrees
F3 Active above 95 Degrees
F4 Active above 98 Degrees
I'm using a 15 minute timer for each of these setpoints, temperature has to be over that point for 15 minutes for fan operation to kick in.
That's the easy part. The part I'm having issues working out is the drop in temperature operation.
Say F4 is active currently. They don't want it to drop to F3 until the temp has been below 85 degrees for 15 minutes. So if the temperature suddenly drops below 85 and stays for 15 minutes it goes to F3 operation, if it stays for 15 minutes again it goes to F2 operation.
I was thinking about using a BSL/BSR operation but not sure if I'm thinking about this the right way.
Timer for under 85 degrees set to 15 minutes. Use the done bit to trigger a BSL. F1-F4 operations are active depending on where the bit is in the bit shift operation.
I can't seem to work out how to get the Temperature up bit shift right to work with the different temperature ranges though.
Is this something that should be done with a sequence operation maybe? Am I missing a super simple way to do this and overcomplicating it?
Programming done in Studio 5000 - compactlogix processor.
There are some Supply and Exhaust fans I need to control (4 of each) to keep a room temperature around 90 degrees. They have 4 combinations of fans they want to run depending on temperature. I'm calling these F1 through F4. Fans are all on or off, no speed control, just a digital output to a motor starter in MCC.
F1 Active below 85 Degrees
F2 Active above 90 Degrees
F3 Active above 95 Degrees
F4 Active above 98 Degrees
I'm using a 15 minute timer for each of these setpoints, temperature has to be over that point for 15 minutes for fan operation to kick in.
That's the easy part. The part I'm having issues working out is the drop in temperature operation.
Say F4 is active currently. They don't want it to drop to F3 until the temp has been below 85 degrees for 15 minutes. So if the temperature suddenly drops below 85 and stays for 15 minutes it goes to F3 operation, if it stays for 15 minutes again it goes to F2 operation.
I was thinking about using a BSL/BSR operation but not sure if I'm thinking about this the right way.
Timer for under 85 degrees set to 15 minutes. Use the done bit to trigger a BSL. F1-F4 operations are active depending on where the bit is in the bit shift operation.
I can't seem to work out how to get the Temperature up bit shift right to work with the different temperature ranges though.
Is this something that should be done with a sequence operation maybe? Am I missing a super simple way to do this and overcomplicating it?