COMMUNICATION WATCHDOGS

The communication status can be monitored through some ONSPEC variables used as Watchdogs that could be shown on the ONSPEC displays. They are DII[index], EUR[index] and FLG[index], where index equals to the driver number specified by /D option plus 127.

For example, /D1 will be the first ONSPEC driver running in the computer and their Watchdogs are DII[128], EUR[128], and FLG[128]. The explanation of these Watchdogs is as follows:

Communication Status Flag: DII[index]

DII[index]=ON (or high, or binary 1) if the I/O template is running in its normal working status.

DII[index]=OFF (or low, or binary 0) if the I/O template is NOT running or there is a time-out indicating that the communication is not working. For instance, if the template is running but the cable is broken. Then, the communication is disconnected.

Message Number Indicator: EUR[index]
EUR[index] saves the running total of the number of messages reported to ONSPEC. If this is ever zero, communication is down.

Overload Flag: FLG[index]
If FLG[index] is high, it indicates that the template is processing so many inputs from the device that it is overloading the queue it uses to communicate with ONSPEC. This means that the load on the template needs to be lightened or spread out more evenly over more polling periods, otherwise data will be lost.



Prev Next