gx developer analog output help

[Matnim]

Hi, I'm trying to programme a gradually increasing analog using and fx1n and a fx2nda unit. The output needs to increase over a set period of time and then hold at the final value. Can anyone Help? Cheers, Matt

[JRoss]

Not a lot of information there about the actual application. I've done similar ramping by using a self-resetting timer. Each time the timer completes, increase the output value by a set amount. Use a comparison instruction to disable the increase once you've reached the final value. The length of the timer and amount of increase determines how fast the ramp happens.

[Matnim]

It's to control the speed of a hydraulic motor which is controlled by an analogue amplifier module. I am having difficulty with the commands in the program, do you have a example of your program. Cheers, Matt

[JRoss]

It's a proprietary program, and not at all the same application (for heat ramping), so I can't give you the code. But you could keep it really simple and do something like: M8012 ---| |-------[<= D0 D10]----------[ADDP D0 K5 D0]----- Where D0 is your ramping value that you then write to the analog output, and D10 is the end goal. M8011 is a special clock bit that cycles on and off once every 100ms. I used the pulsed version of the ADD instruction so that it only increments once. I set the increment constant to 5, so change that based on how fast you want the ramp, or make it a data register if you need to be able to change the ramp speed.

[bobtalbot]

How about the RAMP instruction?

[JRoss]

Um, yeah, how about that! I work in other platforms enough that I occasionally forget some of the purpose-built instructions in Mitsubishi!