Hello, Has anyone setup an FX3U as a Modbus Slave and communication from a 3rd party device as the Modbus Master (i.e. PC) ? For hardware I am using an FX3U-32MT/DS with an FX3U-485ADP-MB on the left-side. Based on the "FX3U Series Communication Manual - MODBUS Edition" I have tried the following: 1. wrote only the logic to establish the FX3U as a Modbus Slave (see attached for communication detail). 2. wired based on the 4-wire diagram in the Mitsubishi manual: from the 485ADP to a 'B&B electronics USPTL4, (RS-485 / USB adapter), to a PC I used the 330 ohm dip switch setting on the 485ADP, and 330 ohm terminating resistors on the USPTL4. 3. Tried reading from the FX using several different widely available 'Modbus Master' programs running on a PC. With the following results: - On the 485ADP I see the RD light flash each time I try a read from the PC, but get a timeout error, (no response from PLC) - If it will help, I can post the various bits & registers in the PLC, but in summary; I see D101 (bus comm error counter) increment with every read from the PC. However, D8402 (Modbus Error code) is zero. Also I have tested with many variations of the above: Changing: baud rate, Slave Address, 2-wire and 4-wire, with and without terminating resistors, RTU / ASCII Tried all different Modbus read commands: (0x01, 0x02, 0x03, 0x04) Is there any other programming necessary on the FX3U to respond to requests from a Modbus Master? Any suggestions you can offer will be appreciated. Thank you, Jim
