PLC COM Ports

[cmarcus]

Hello Support Team,

I've got a V130 T38 PLC. I've been writing .NET application to load recipes to the PLC's for years now. I've been using the Active X control as well as the .NET DLL. Both have been working perfectly right up until recently.

Here's what I've got going on. If I run any application that communicates to my Vision 130 PLC. I connect to the PLC using the serial port. If I immediately begin to write / read data, no problems. If I leave the connection open for a period of time (say 1 minute), then attempt to transmit data the PLC stops responding. I used a serial port monitor, and do not see the port being closed on the PC side, it just looks as if the PLC times out and then won't respond. The .NET DLL responds back with "Could not communicate with PLC"

I've tried the following:

- Three different PC's

- Two different PLC's

- Visilogic v8.6, v9.2 (with associated OS's).

- Active X DLL

- .NET DLL (with the the sample program provided with the DLL).

- Connecting directly off of the PC's RS-232

- Connecting through a USB to RS-232 converter

The programs that I've written in the past (written in Visilogic v8.1 and associated OS) DO NOT exhibit this behavior. Any help would be greatly appreciated.

[cmarcus]

Update: I removed the current Active X DLL and took the active X DLL from one of my older applications that is working. Suddenly everything starting working just fine.

So I guess the question is, have there been any revisions of the Active X and .NET DLL recently? Looking at the file properties, both the one that timed out and the one that did not time out were version 1.38.0.0 and the file sizes were the same.

Again, any help would be appreciated.

[cmarcus]

Ok last one today, I promise.

When I capture the exception message in the .NET DLL it says the following: "Cannot communicate with the PLC with the specified UnitID!"