Persistant data on allen bradley high speed counter

[einnh]

We have two staggered prox. sensors hooked up to an allen bradley vhsc24 point io module. They are counting up and down in encoder mode due to being staggered.

The problem I am having is the count resets on power cycles. Is there a way to pull in the last known position on power-up via some hardware variable or logic?

Using CLX.

Please assist!

Thanks

Eric

 

[bernie_carlton]

In the program store the current value. On restart store the recorded value to Preset (Configuration Word 11). Then trigger the Counter Preset output bit. There may be more to this (especially setting the preset value) than this simple description shows. Note: this is just from reading the manual tables and familiarity with other AB counter modules.

 

[rdrast]

For CLX, my favorite method of handling any counter module is to pass the count through a PMUL instruction, with a word size of 8 bits, and then in the same task, accumulate the output of the PMUL with an ADD instruction.

On power-up, I disable the ADD instruction for a couple seconds to prevent false counts, and you can easily run multiple counters off of one physical counter (say, run footage, shift footage, day footage, etc).

This method works with any counter module without any special programming or wierd reset/preset handling.