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VISA vs TCP

I just checked on our Mettler balances.  They have a serial RS232 output.  We run them through a box made by Comtrol that turns 16 serial devices into a TCP/IP network stream.  Unfortunately, the PC that talks to these balances doesn't have MAX functioning, so I'm not quite certain how these things appear in MAX (we may have had to do "some magic" for MAX to see them).

 

Anyway, in MAX, we assigned each of the TCP/IP ports from the two Comtrol devices a I/O Device name, such as Mettler_A_01, which we then used in the VISA Open call.  So all we needed was the IP of the two devices, and we were in business.

 

Bob Schor

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My puny mind is going to have to read this a few times in hopes of understanding what exactly you did.

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There's a box that can accept, say, 8 DB-9 serial connectors.  The box has an RJ-45 socket into which you can plug an Ethernet cable.  The box has an IP, say 192.168.5.25, and has 8 ports (such as 192.168.5.25:001).

 

You connect your serial devices to this box.  Your PC has a NIC that is connected to the same network (the 192.168.x.x network) as the remote box.  Using TCP/IP commands, you can treat this "port" as though it were a VISA device, and use LabVIEW VISA functions to do whatever you want to do with it (VISA Open, Read, Write, etc.).  The VISA code is no different, just how you "address" the Serial Device (using an IP rather than COMx).

 

Bob Schor

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