PLC5 to RSLogix5 update rate slow

[JesperMP]

One thing I just thought of:

If you check the main PLCs code for the MSG instructions to the troubled PLC, are they triggered by the DN bit of the previous MSG instruction to the same PLC ?
If that is so, the result will be that the PLC that responds to the MSG requests will work 100% on the channel, because there will allways be a new MSG instruction when the previous one finishes.

In that case, increasing the time slice will only mean that the troubled PLC will be just as bogged down with MSG requests as before, only it will be sending a lot more. It will probably then be the PLC that sends the MSG requests that becomes the bottleneck.

Also, I think that the most normal way to make MSG requests is to trigger them by event or by time (and not too frequent).

 

[russrmartin]

Jesper,

This is how our MSGs are triggered. Just for fun I did try to adjust the time slice, which had already been set at 10. I bumped up to 20 and down to 0 and saw no change whatsoever in update rate. I will do some searching on the MSG instruction and see if I can manipulate when we are using that to try to speed things up. Thanks a ton for the info.

Russ