Nugro Posted March 13 Report Posted March 13 Hello everyone, Need your assistance. I'm trying to read data from several modbus device via RS485 - Ethernet Converter (USR-DR302). I have 2 Temp controller (Modbus ID 3 and 7) and E&H Flowmeter (ID 15). Testing connection with Modscan32 works well. I can read data from all the devices. Now I want to read those data to FX5U PLC via ethernet (Modbus TCP/IP). I'm trying to use simple comm setting not works, use Modbus tcp (External device config ) also not working. Is there any way to read those 3 devices to FX5U ? Thank you Quote
Goghie Posted March 14 Report Posted March 14 Modbus RTU and Modbus TCP/IP are different protocols., so if you are using Serial to Ethernet converter and connecting RTU devices to Mitsubishi Ethernet port, you are doing it wrong. FX5U has both serial and Ethernet ports, and supports both RTU and TCP/IP. Modbus supports multidrop (many slave devices). 1 Quote
Nugro Posted March 15 Author Report Posted March 15 @GoghieThanks for your answer. Just want to know if RTU to Ethernet converter can work. Anyway, Multidrop and TCP/IP from device i did earlier working without any problem. Thanks Quote
Wasan Posted March 16 Report Posted March 16 @Nugro I have check this device feature on product site https://www.pusr.com/products/din-rail-rs485-serial-to-ethernet-converter-usr-dr302.html I think it can config to be Modbus gateway then you can use Modbus TCP on Predefined protocol or Simple communication function in FX5U to communicate with device. Quote
DanW Posted March 16 Report Posted March 16 As long as the specs say that they'll support Modbus RTU, which has very specific timing requirements that can be a problem for generic serial-to-Ethernet converters. Quote
Goghie Posted March 17 Report Posted March 17 As I understood, OP used only serial to ethernet converter that is connected on ethernet side directly from output of the converter to the FX5U ethernet port. When PC is used there is the Virtual Serial Port software as middleware, with PLC there is no additional driver that will convert from RTU to TCP, so this configuration is not applicable. Quote
Solution Crossbow Posted March 17 Solution Report Posted March 17 Use an RS485 module on the PLC. Why try to mess around with Ethernet? Waste more time trying to develop something custom when the PLC already has support for Modbus. Quote
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