crono141
Member
Hi everyone. First time poster here. I am very new to PLC programming (my programming background is more in computers). I have a question with regards to the functionality of the unlatch bit operator (OTU) on an AB Micrologix 1400.
I have a number of bits which are control bits used for HVAC control over modbus tcp. I have some logic that turns these on and off based on sensor data, but this logic is blocked during an emergency stop situation. But in an emergency stop situation, I want to set all of these bits to off. Based on reading various forum posts and the Micrologix instruction set, unlatch appears to be the operator I need to use.
Here's how my logic looks. I have a bit that is energized when E-stop is triggered. Behind that bit on a rung I have the unlatch operators for my HVAC control bits above.
My question is, if an estop is triggered and all these bits are set to off, if the estop is cleared (and the rung with the unlatch becomes inactive) will the other logic in the program that normally addresses these bits still be able to modify them, or will they remain in the off position?
I have a number of bits which are control bits used for HVAC control over modbus tcp. I have some logic that turns these on and off based on sensor data, but this logic is blocked during an emergency stop situation. But in an emergency stop situation, I want to set all of these bits to off. Based on reading various forum posts and the Micrologix instruction set, unlatch appears to be the operator I need to use.
Here's how my logic looks. I have a bit that is energized when E-stop is triggered. Behind that bit on a rung I have the unlatch operators for my HVAC control bits above.
My question is, if an estop is triggered and all these bits are set to off, if the estop is cleared (and the rung with the unlatch becomes inactive) will the other logic in the program that normally addresses these bits still be able to modify them, or will they remain in the off position?