I am attempting to establish a connection between a Mitsubishi FX3U PLC and a Mitsubishi FRD-740 inverter via RS485 serial communication, utilizing the FX3U 485BD module on the PLC side. The inverter is equipped with a PU connector. I'm wondering if this PU connector can facilitate communication with the inverter, or is it solely intended for connecting to a computer? I've tried to set it up, but I’m not receiving any response from the inverter. I’ve consulted the manual, but the information provided is somewhat unclear. Any insights or guidance would be greatly appreciated. Thank you!
Absolutely, it is effective! You have the option to utilize either the Mitsubishi inverter protocol or the Modbus-RTU protocol, with Parameter 549 configured to 1. This communication method operates over RS485.
It sounds like you're on the right track, but the confusion with the PU connector is common. Typically, the PU port on the FRD-740 is indeed meant for configuration and monitoring via a computer with appropriate software, rather than for direct RS485 communication with the PLC. You should look into using the dedicated RS485 terminals on the inverter instead. Double-check the baud rate, data bits, stop bits, and parity settings on both sides, as mismatches there can often result in a lack of communication. Additionally, ensure that you have the correct wiring setup and that your grounding is solid. If all else fails, reaching out to Mitsubishi’s tech support could provide you with some specific troubleshooting steps. Good luck!
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Answer: - Check the wiring connections between the PLC and the inverter to ensure they are correct and secure. - Verify that the communication parameters (baud rate, parity, data bits, stop bits) are correctly set and match on both the PLC and the inverter. - Ensure that the inverter is configured to accept communication commands through its serial interface.
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