modbus RTU via ATEN usb to serial

[shai-bgu]

Hi, I have a working program that reads\set Fried Electric Heat plate temperature through native serial port

This works fine. Now I need to replace this native com with usb to serial and so I did. I have installed its new driver and verified it appears in device manager ac com4 with the parameters as com1.

I have selected com4 instead of com1 in the vi but I'm getting Error 56 occurred at SubVIs.lvlib:RTU Data Unit.lvclass:Read ADU Packet.vi:5030001 when I run it.

Any ideas?

[l.hovs]

Hi shai-bgu, 

This timeout error can be caused by configuring the TCP/IP functions incorrectly, and can often be cleared without detriment, as long as the data is being received. If the data is not being received, there are several troubleshooting steps below to mitigate this error. Follow this link to find troubleshooting steps. 

Regards)

________

Best way to thank is to give Kudos.

[shai-bgu]

Thanks for your input. However I am not using Tcp/ip. As I noted Im using serial mode. 

[l.hovs]

If you are doing Modbus over a serial connection, please make sure that the connection between the serial pins on each end is correct. Try to change the pin to right the right one. You can check it from NI MAX as well by doing a self-test. 

Regards)

[shai-bgu]

Hi Hovs,

We are talking about a ATEN usb to serial dungle https://www.aten.com/global/en/products/usb-solutions/converters/uc232a/

I can't really change physically the pins connections in it.

I was thinking to buy a pcix serial card or a cable that can extend the onboard serial connector to a com connector.

[MaSta]

What he most likely meant: if you use a USB-to-serial cable, where "serial" usually means RS232, then it has a male D-Sub9 connector and on the target you have that as well. When connecting two male connectors you need a cable or an adapter. These can wire the pins 1:1 or switch RX/TX (null modem). Should that be the cable that you used before you switched to USB, then it's proven to work, unless the actual ports on both sides are RS485. 

[shai-bgu]

Hi

Thanks for the response.

The heat plate comes with a cable that has a RS232 female connection, so I didn't need an additional connector. If such usb to serial dongles works fine with modbus communication than maybe this new dungle is DOA or its driver is not compatible with modbus.

Is it possible that the manufacture ATEN usb to serial driver will not be modbus compatible?

[l.hovs]

Hi again, 

I am not sure about the compatibility, because there are not any articles about compatibilities from NI side, therefor you can contact ATEN support and ask them question about this kind of compatibilities, they may have relevant documentation or solutions in this case. 

Regards)

[MaSta]

Female RS232 on the device side is unusual. I found Fried Electric (seems to be from Israel), but their user manual doesn't even show the RS232 port, nor describes about it. What a poor website!

For instance, the HP-400 model is supposed to have RS232. Sure, with the device having a female connector and the adapter cable being male you would simply plug it. I would do the same. But it still could mean that you would have to use a null modem cable that switches RX and TX signals. Good, that the user manuals of that company tell you everything you need to know...

However, it seems this topic isn't a LabVIEW problem.