Rslogix 500 help with logic

[bearsgone 1]

Hello I have a 3 blower logic. Two modes. Mode is changes by pressing a button on a HMI screen, program is on ML 1400. Mode ONE: One blower at a time. 3 blowers total. Each blower goes on and off for a set period of time. Next blower comes second hour, and third blower comes on third hour, fourth hour first blower comes back on again. If running blower fails(contactor), next blower picks up until first(or which ever turn) blower is fixed. Mode TWO: Just like mode one except that two blowers run 2 at a time such as AB - BC- AC. If any of running blowers fail, third spare blower comes on. The problem: In a situation where I am in a single blower mode, if a single running blower fails, instead of another single blower turning on, I have two blowers turning on. As soon as failed blowers(contactor) is fixed, everything goes back to a single blower mode. Somewhere I am crossing fail over logic between single mode and double mode but do not see where. I hope my confusing description makes sense. I also have an oxygen sensor that dictates when blowers turn but please ignore that. Any suggestions would be greatly appreciated! Blowers.pdf Edited 4 Feb 2011 by bearsgone

[mhowasso 5]

It would be easier if you would post the actual program file. Where is the coil bit for B3:21/6..???

[Michael Lloyd 85]

Programmers crack me up... myself included. We always protect our "stuff" like it's the only version out there

[bearsgone 1]

Coil bit B3:21/6 is on HMI. it is a two state button 0 and 1. So the end user chooses in which mode blowers will operate by pressing a button on HMi screen which in turn sets a bit for B3:21/6. The rest of a program has no references to this blower logic.

[OkiePC 14]

In each single blower branch, you need to add logic so that if, for example, Blower_B is faulted and Blower_C is not running, then run Blower_A, etc. The way you have it programmed, any time a blower is faulted and you're in single blower mode, both of the other two blowers get told to run. Edited 4 Feb 2011 by OkiePC

[Qwert 0]

Another option to fix your problem. Remove Fault Blower B from single mode operation for Blower A. Remove Fault Blower C from single mode operation for Blower B. Remove Fault Blower A from single mode operation for Blower C. This wlll allow a single blower to be the standby in case of a fault. In case of 2 faulted blowers the 3rd blower would operate.

[bearsgone 1]

Hello I am still missing something. The issue is that if one of the blowers is in hand/HOA, program should ignore it. So in a single mode or two blower mode, if any of blowers are in hand, they should be ignored. I can not seem to figure out a way to accomplish that. Please help! ML1400 UNTITLED.pdf UNTITLED.RSS

[Shiner 2]

Program seems complex for this app. You could go with an add statement to a N register (1-3) and use the Equal compare to determine which motor to turn on in single, and which to turn on in double. To reset the cycle use if equal to 3 and timer complete move 1 to N1. Then in your output rung if you have a fault add one to N1 to move to the next blower. If it cycles around before fault is repaired it will just pass it by again. For the two blower mode each truth statement should be If in double and value of N1 is 1 or 2 for Blower A and not in hand then run or if faulted or in hand add 1 to N1