RSLogix GSV/SSV

Hello,

So I thought I understood how to communicate with I/O modules in RSLogix5000. I thought that you would declare an I/O module and simply alias the hardware tag to some other tag you would use in the program.

However, I've been looking through code recently and have seen the use of GSV/SSV for interacting with the I/O modules.

This confuses me. I know that the GSV/SSV is meant for objects(I have some experience with using them for axis objects), but I never thought that you would use them for I/O.

So, could anyone explain to me the purpose of the GSV/SSV and why someone would use those instructions as opposed to using the declared hardware tags that are available when you add a module to your project?

The GSV/SSV are used to read status of the controller's connection to the module. Using the GSV you can identify if the module is running, faulted, or inhibited. If it is faulted, the GSV can capture the fault code.

OG

The GSV and SSV are often used to interact with the status of an I/O module itself, one level up from the I/O data. Readiness status, specific errors and other information can be read. In some cases the program can correct module problems or at least performs resets.

I often use the GSV commands to read the status of communications with external remote modules (drive interfaces) which may take a while to connect with the end targets (the drives themselves). Only when they are ready can commands to the drives take place.

bernie_carlton said:

The GSV and SSV are often used to interact with the status of an I/O module itself, one level up from the I/O data. Readiness status, specific errors and other information can be read. In some cases the program can correct module problems or at least performs resets.

I often use the GSV commands to read the status of communications with external remote modules (drive interfaces) which may take a while to connect with the end targets (the drives themselves). Only when they are ready can commands to the drives take place.

Click to expand...

Okay, that seems to make sense then. Thank you