AB Sequencer Problem

[cgossett]

I'm having a problem with an AB Micrologix 1000 program that utilizes a sequencer (SQO) to alternate the operation of a series of lights. I'm fairly new to PLC's, but I understand ladder logic and have been successfully modifying previously-created programs as needed for new applications. I want to revise an existing program that sequences five lights(SQO Length=5) to one that sequences six(SQO Length=6). The original Length 5 program works fine. But in the Length 6 program, the output bit for position six never gets set, so the sixth light is never turned on.
Any suggestions out there?

 

[ADMIRALKEN]

If you could post your code, it would be easier to help.

There are several possible causes to your poblem.
1. SQO moves 16-bit data from one memory location to a word address, do you have the correct word in the source location?

2. SQO has a bit mask feature, perhaps you are masking the 6th bit. Is anything entered in the mask box? If the mask box has a file location instead of a hexidecimal value, you must have a mask word for each index, the mask file indexes with the source file.

3. Is the proper length been set? What is the current value?

 

[cgossett]

Thanks for the help. We found the error in the source file. The sequencing works as expected now.

 

[chakorules]

Hmm..I agree, Can you post your own code? If all else fails, look at an example. You can download a sequencer example here:

http://www.mrplc.com/cgi-bin/code/filedisplay.cgi?category=machab

It's called PicknPlace Sequencer

Good luck!
Chris

http://www.mrplc.com

Chris Elston
Automation & Controls Engineer

http://www.mrplc.com