User`s guide

Page 52

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

5.4. Tables [1



20] … Actuator Information Tables

5.4.1. Table [1]: Communication Error Status

Words [4

 63] PLC access: Read Only.

The “Communication Error Status Table” is used by the network master to track communication faults

with each actuator. This data is totally derived by the 1746-C. These are considered “Low-Level”

communication errors.

The value of the word gives the following status:

• 0 = good communication through both ports

• 1 = error communicating through Port 1 … but success on Port 2

• 2 = error communicating through Port 2 … but success on Port 1

• 3 = No communication to the valve actuator at all. In this case, bit-14 in Table [2] will also

be set.

This table can be used by the PLC system to diagnose valve actuators that are not communicating. If

a network requires maintenance, then information in this table can help trace the problem. During a

network fault, this information can help point to the section that’s in fault.

During communication with the actuators, a time-out value is implemented to flag network errors. The

network master will try to communicate with the valve from the currently “preferred port” three (3) times.

If the valve does not respond within those three times, the valve is flagged to communicate on the

current “backup port” and the 1

port is identified as having a problem with that valve (in table [1]).

The backup port immediately tries to communicate with the valve three more times. If the valve still

fails to respond, the particular actuator is flagged as having a general communication error by having

• Its table [1] entry set = “3”.

• Its bit-14 in table [2] set = “1”.

The data in this table is always updated … any time the 1746-C tries to communicate with the network.

However, this table is only reset (errors cleared) during a diagnostic scan.