GE PLC program ?

Hi all,
Never did this before so please advise on this. Have a GE 90-30 PLC CPU 363 comm. with an HMI running Cimplicity. The operator inputs a dip depth into the HMI to adjust the depth an axis will dip. This number gets dumped into a %R register. Now, if I want to limit this depth to a certain value other than what the operator has input if a sensor is made on the machine can I just do a move instruction when the sensor is made which will move this new value into the register and overide the other value. If so, when the sensor is not made how will the old value get back into the register. Would the operator just need to input it again on the HMI. Thanks

If I'm getting what you're saying correctly, your signal from the sensor is going to be discrete, correct?

If so, just use that bit to interrupt your operation.

If the allowable depth varies with the part being dipped, its probably better to make your sensor modify the target depth for the move rather than act as an overtravel switch or software travel limit.

Maybe you could add a "Test" button on the same HMI page where the operator sets the depth. He keys in a number and hits the "Test" button which moves the part to the depth he keyed in unless the sensor is tripped first.

Or maybe "Jog Down" and "Jog Up" buttons along with a position display so the operator can jog the part down until just before the sensor detects and use that to set his dip depth.

Have the hMI write to another unused register. Then with a rung of logic depending on the status of the sensor either move the HMI value or the overriding value into the final register position. It would be good to give some feedback to the operator that an override is occuring.

Thanks guys for the help, I think I am envsioning what Bernies is saying. I will add another move int instruction in the program which will ultimately move either the HMI dip depth or the other value we chose ( Doesn't need to be adjustable by the operator) depending on sensor staus to the servo.

One other note that is a bit confusing as I don't get involved in this all te time. When veiwing on-line we have a Mov int instruction ( 2 in length) that shows he input data as 12000 and the output data as 12000.In the next rung there is another mov int ( length 1) which takes the 12000 and moves it into another register but the value is now 224. Can you explain that a bit why the data is a different value. Thanks for all the help.

It's hard to tell without being able to see more of the program, but if the destination addresses of the MOVE_INT instructions are %AQ locations, the rungs could be sending commands and data to the motion controller module. Most likely some different value is being written to the destination address of the second MOVE_INT instruction later in the logic.

The most likely reason the value is no longer 12000 is that the second register is also written by another rung in the ladder logic. For example, we will have a 'temporary' register that we re-use over and over to do intermediate calculations so the displayed value in the monitor is really essentially garbage since its written multiple times each scan.

Try searching for all instances of that register: you'll probably find another rung that also does a MOV into that register (or a timer, or pid, ...). That second register could be in the middle of a BLKMOV too.