You can determine the status of the PLC module using the GSV function block. below is the snippet of how you would use the function block.
If the module is health, you will get a response of 16384 (decimal); and in hexadecimal it would be 4000x.
The result of 16#4000 (or 10#16384) means that the device is Running. All connections to the module are established and data is transferring. See page abstract from the Logix 5000 Controllers General Instructions Reference Manual (page 219). The link to this document can be found below in Reference section here.
When EntryStatus GSV is returned and properly masked it has several options but most often the primary purpose of using the instruction is to identify if the module is in good condition and the project can rely upon data it delivers.