RV3.1

Z-value extension to register addresses on PLC program Qseries

4 posts in this topic

We have a QSeries PLC. Q25HCPU. We also have a PLC program. We found that the address registers (also known as device addresses) attain a z-value added next to it - automatically over time. We are not sure why this is the case. Nonetheless, when these values get added (by the PLC - not the engineering software), some of the functions in the PLC doesn't work. We found that by formatting the CPU, and reloading the program, allows for the system to work again (temporarily) for a few weeks, up until this problem occurs again. This problem occurs across various CPUs (eliminating the potential for hardware problems.

These z values can be seen when a program comparison is done. (see attached file).

The questions become;

1. What is the function of these values? (why does the PLC add them?

2. How can they be permanently removed?

Zvalues.png

Share this post


Link to post
Share on other sites

Posted (edited)

This are index registers. They are  not added by the PLC!!! they are part of your program.
So if you have D15Z0 . this means that if the vallue of Z0 = 14 Then the device being used is D29 (15+14).

Looking at the devices being used it looks to me that the original project uses a FB and you are looking at the compiled code

 

 

 

 

Edited by Gambit

Share this post


Link to post
Share on other sites

Thank you for the reply Gambit. Thing is, the table above is attained via a program comparison. The table on the left shows the code as is on GX developer. The table on the right shows the code as is found on the CPU. The additional Z values are not being added by the user, as can be seen by the left table.

 

Share this post


Link to post
Share on other sites

Are you sure you are using GX Developer and not GX IEC Developer ?

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now