User`s guide

Page 9

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

PRT1 & PRT2 (Green) LED App Note: Green LED Lights & System Initialization with Table [0]

After startup, if table [0] is not initialized shortly after the 1746-C finishes its initial diagnostic

scan, the program starts running with factory default settings. This means that unless the

network actually has 60 actuators on it, the 1746-C will believe the “other valves” are just off

line.

Plus, an operator can often determine when the PLC-RLL actually writes to table [0] (configures

the system) by watching the green LED lights.

For instance …

• On a network that actually has 25 valves on it (addressed 1-25), until table [0] – word [4]

gets initialized with 25, the program thinks that there are still supposed to be 60

actuators on the network … only the last 35 happen to be “off line”.

• Then (if viewing the green LED lights) when a scan starts (LED1 changes state), you will

see the green LEDs “flash” while the 1746-C communicates with valves 1-25.

Then you will observe a “dead space” in time when the program is trying to determine if

any of the final 35 valves “it believes to be connected” are available (

and of course none

are because the network only has 25 valves on it

• As soon as a new scan starts (all “60” valves have been checked and ready to scan the

network again … LED1 changes state) then the green LEDs will start flickering again

while the 1746-C communicates with valves 1-25.

Then the “dead space” time will be observed again.

This sequence will repeat until the PLC program initializes the 1746-C by writing to table

[0].