Forcing Analog Values in LogicMaster 90-70

Good afternoon,

I am conducting some tests on GE 90-70 PLC following some code modifications with LM90-70.

In the reference tables I can force digital inputs no bother, however I want to force an analog value but can't seem to. I read the manual and apparently you just enter the value you want and hit "ENTER" but that doesn't seem to work.

Any ideas welcome and have a good weekend

You can't force analog values in the 90 series the way you can discretes. The reason you can't just type in a new value into a %AI memory is that the analog input module overwrites with the data from the sensor every scan. You could add a rung like this at the beginning of your program:

 Force      ______

--] [------|      |

           | MOVE |

           | INT  |

    Value -|IN   Q|-%AIxxx

           |______|

"Force" is any available discrete memory address. "Value" is any available %R address. When you turn it on the MOVE function will copy the data in "Value" to the analog input signal. Since the module is updated before the program scan, the data from "Value" will overwrite the data form the analog input module.

Turn off "Force" to revert to the module data.

Many thanks Steve.