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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 (support@eztcp.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 > > >

Writer	Sollae Systems	Company	sollae