JSR - Modicon Momentum

[Disar]

Hello, I am rewriting some code and would like to start using JSR instructions for functions I perform regularly (zeroing out entries on the HMI, searching for model numbers in a data table, etc.). I have several questions I was hoping you experts can help me with.

1. I have read over the pdf file for the JSR command and how it is used. It talks about criteria for segments for the JSR to work properly. Could someone explain this to me?

2. What is the difference between a segment and a network? I am sure it is the hierarchy of the program structure. My problem is it seems that the program I am updating is one long segment (160 Networks).

3. If I were to implement JSR's into this program would I have to restructure it so I could so I could add in these segments?

4. I am sure you can do this but want to make sure. Can I power on an output in a SR and when I returnuse that output in my program? Or is the JSR command used to perform data manipulations?

5. What do you typically use the JSR command for? In a program do you use it often? Does it slow down the system if used to frequently?

6. Are there any examples of how the JSR is used online?

I appreciate all of the help.

Thanks!

 

[Jim Dungar]

The JSR command jumps to a specified segment as opposed to a "subroutine block" like other processors.

In Modicon 984LL the program networks are actually contained in segments, The Segment Scheduler is used to determine the logical solve order of the segments as well as the assignment of which remote Inputs to scan before solving and which remote Outputs to write after solving the segment. This allows the program to update the I/O as the logic is solved rather than having to wait until the end of scan. This was a nice feature for improving the effective scan time as you could solve the same segement several times in one scan.

With the advent of faster processors this feature is not as important as it used to be.