User`s guide

Page 90

Controlinc 1746-C (Version 5.21) Network Master Users Guide (2004-11-18)

6.1.4. Behavior if a Delay in Loading Table [0] Configuration Information

The 1746-C does not store configuration information if power is cycled. When the 1746-C restarts, it

reverts to factory default values (60 actuators, 50-Scan Period, …).

It is the responsibility of the PLC to ensure that system configuration information is written to the 1746-

C. The PLC should periodically read the configuration back to ensure that the 1746-C still has the

correct configuration in it (the 1746-C module was not reset).

Example:

Assume a network of 25 actuators.

If power is cycled on the PLC, the 1746-C will revert to factory default values (60 actuators, …).

The sooner the PLC can reload the correct Table [0] configuration, the sooner the 1746-C will

start polling the correct number of units.

Until this happens, the operator will see what appears to be a “dead space” in the transmitting

and receiving of data when watching the tx/rx LEDs on the 1746-C module. What happens is

that:

1. A diagnostic scan has determined that only 25 of 60 actuators are on line.

2. A new scan starts.

3. 25 actuators are communicated with.

4. The 1746-C steps through the next 35 actuators … preventing communication to them

because they are “off line”. This is the “dead space” when watching the LEDs.

5. The scan ends … go back to step #2 if not at the end of the scan period.

In this situation, the operator will see a very regular pattern of “dead space” on each scan (each

time LED1 changes state).

Solution: Ensure the PLC writes the configuration information and periodically ensures it stays correct.