Rockwell Automation 1779-KP5_KP5R ORD.1779-5.3 - Manual (Page 62)

1779ĆKP5 Troubleshooting Tools
Chapter 6
6Ć7
The following sections tell you:
What a Diagnostic Counter Is
How to Read Diagnostic Counters
What 1779-KP5 Diagnostic Counters Contain
What is a Diagnostic Counter?
A diagnostic counter records an event of interest for debugging the
module and for longer term reliability analysis.
Since Data Highway II uses application layer diagnostic counters, the
1779-KP5 does not have diagnostic counters for Data Highway II.
However, the 1779-KP5 does have counters for Data Highway Plus.
The diagnostic counters occupy a block of the module’s internal scratch
RAM. Most are single byte counters that reset to zero when they
overflow.
These counters provide a useful tool for diagnosing problems.
How to Read Diagnostic Counters
To read diagnostic counters, you must issue a Diagnostic Read command.
This command can only be sent from a device:
Connected to a Data Highway Plus with an interface module that
supports an asynchronous port.
That can format the diagnostic commands.
Therefore, a PLC user program is unable to initiate a Diagnostic Read
command.
Important: The location of the diagnostic counters in a Data Highway
Plus module varies:
From module to module.
Between revision levels of the same type module.
You must first request the location of these counters by transmitting a
Diagnostic Status command to the module. Based on the address
returned, you can use the number of the counters which follow as an
offset to calculate:
The location of a particular counter.
How many counter values you want returned.
1779ĆKP5 Diagnostic Counters