1734 PointIO module - can it go into default mode if connection is lost?

[ryangriggs]

I'm working with a 1734-AENT PointIO module (manual) connected to a 1769-L30ER controller over fiber ethernet. The 1734 PointIO module has some analog outputs that control some valve actuator positions in a remote building, far from the main controller.



If the connection between 1734 and L30ER PLC is lost, it could cause major problems if the valves were left in their positions without being monitored and modulated by the PLC.


Is there a way to configure the 1734 so that if it loses network connectivity to the PLC, it would place the analog outputs into a default state (in my case, output 4mA to close the valves immediately)?


I realize that within RSLogix5000 I can configure the PLC to go into a Major Error state if comms are lost to the module, which would be good, since we could be alerted to the issue, but someone may not be able to get to the site for a long time, which could lead to overflows if the valves are left unmonitored for that time.



Thanks for any info or suggestions.

 

[joseph_e2]

I've never used Point IO (when I had a good application for it, it was unobtanium), but if you go to the module properties for the analog output module and the Fault/Program Action tab, you can tell it to go to low clamp upon fault. There's another column for program mode action. Not sure if loss of network connectivity will result in a fault that the 1734 chassis can detect or not (I'd expect so...but you never know). It's probably worth a try.

 

[ryangriggs]

Thanks, I will give that a try!

I've never used Point IO (when I had a good application for it, it was unobtanium), but if you go to the module properties for the analog output module and the Fault/Program Action tab, you can tell it to go to low clamp upon fault. There's another column for program mode action. Not sure if loss of network connectivity will result in a fault that the 1734 chassis can detect or not (I'd expect so...but you never know). It's probably worth a try.

 

[Ken Roach]

Separately-configured Fault and PLC Program Mode actions are an ordinary feature of POINT I/O output modules.

In the Fault/Program Action tab for the 1734-OE4C (Current Analog Output), you can select "Go to Low Clamp", "Go to High Clamp", "Hold Last State", or "Use Fault Value".

In general with the current loop output channel set for 4-20 mA, I would expect "Go To Low Clamp" to result in 4 mA output when the connection fails.