|No. 1699||Re: SMG-5420 - No Signals via Modbus RTU||2019-11-13|
Dear Benjamin Beck,
SMG-5420 device receives Modbus/TCP frame from TCP, converts it to Modbus RTU/ASCII frame and sends it to the serial port, and vice versa.
Seemingly, the date frame you sent via TCP is the Modbus RTU frame, NOT Modbus/TCP frame. Therefore, It does NOT work.
You can refer to Mobus/TCP frame in this document https://www.eztcp.com/en/download/pds_files/an_modbus_tcp_en.pdf
We recommend you to use a Modbus Tool for testing instead of sending raw data for testing.
For more information about configuring SMG-5420, you can refer to this FAQ: https://www.eztcp.com/en/support/view.php?page=1&cid=484
If the problem is not solved, could you please send us via email (email@example.com) the following information:
- The screenshot of SMG-5420's setting
- Modbus configuration of your control unit
And, is your network topology similar to the scheme in this image https://www.eztcp.com/en/support/images/case1.png ?
> Benjamin Beck wrote:
> Dear Madams and Sirs,
> I am trying to connect a SMG-5420 device to control unit via ModbusRTU (RS485). Seemingly, the SMG does not recognize any Signals on TX and RX. I am using the following configuration
> Bd-rate: 9600 bps
> Data bits: 8
> Stop bits: 2
> Parity: None
> SMG working as TCP Server
> Port 502
> Connection Timeout 60s
> Query Flow: TCP to Serial
> Slave ID 0
> Response Time: 500 ms
> Send Gateway Exception: Disable
> When I try to access the Modbus via EzTerm (or similar tools) and try to send
> 15 04 00 02 00 01 93 1E
> The connection is terminated.
> Trying to emulate a Com-Port via ezVSP didn't either.
> Is a 120 Ohm resistor necessary for proper signal termination? What might be the reason for the Modbus Connection problems?
> Best regards,
> Benjamin Beck