RS485 communication

[GerdW]

Hi Neby,

In the manual it says that the MODBUS-RTU protocol of the inverter supports only part of the code, everything will be in binary. This means I do not have to use an Modbus in LabVIEW but I need to do a data conversion, right?

Why do you think you cannot use MODBUS when the manual says the inverter understands MODBUS messages?

Use any of those available MODBUS libraries…

[rolfk]

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@Ben wrote:

Not all RS-485 widgets are created equal.

There are other property nodes for rs-485 to configure 2 vs 4 wire etc.

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The Windows COMM driver interface doesn't support that and therefore it is not standardized. The relevant VISA properties call through custom IO-control calls into the according NI-Serial driver to tell the driver to change the hardware settings for these properties and only the NI-Serial drivers support these custom IO-control messages. Other hardware may have drivers that allow to set their relevant functionality in a similar way but of course not compatible to the NI-Serial drivers, and therefore if you try to access those properties VISA will most likely report an error.

[Neby2]

Hi

So far very helpful, thank you! Unfortunately, I still get an error back, when I try to communicate with the inverter. For the communication, I am using a Modbus. I still get the same error, but way later in the program.

Thanks for the help everyone.

[RavensFan]

That is not the same error.  This one is -1073807360 about "unknown system error".  Your original error was -1073807194 about "the connection for the given session was lost".  They may be similar errors, or completely unrelated.  But they are not the same error.

Unfortunately, this error gives you less details.

I'd suspect you have problems with your RS-485 serial port device.  What brand/model are you using?  I would try a different brand.

[Neby2]

I am using an EX-1309-T. It is a general converter, which you could also use for RS232 or 422.

[Ben]

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@Neby2 wrote:

I am using an EX-1309-T. It is a general converter, which you could also use for RS232 or 422.

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Where is 485 in that list?

While 422 is similar to 485, it is not 485.

If memory serves me, 422 used differential drivers for Xmit and Rcv and therefore could be used for longer wire runs beyond the old 50' limit of 232.

485 came in different flavors (2 and 4 wire) and could be used as a bus to control multiple widgets with termination at the end of the line.

Now it the widget is a 2-wire version, you have to tend to how the control of the line is handled. Ni 485 cards can handle it automatically, under explicit control or by using DTR, aging from memory.

So get your physical details worked out first.

Ben