PLC No Response

[ct8356]

I have downloaded a program into the PLC, downloaded a program in the HMI terminal, and connected my PLC to the HMI via a custom made RS232 cable. When I turn them on, the correct screens appear on the HMI terminal, but no data is coming through from the PLC. After a few seconds, a pop-up appears saying "[2]PLC No Response 00-00-1". Does anyone know the meaning of this message, or what I might be doing wrong or missing out? CPU used: CP1L-M60DT1-D (with a CP1W-CIF01 serial adapter) HMI terminal used: NB3Q-TW00B Details for the RS232 cable: NB pin 2 (SD) to CP1L (CP1W-CIF01) pin 3 (RD) NB pin 3 (RD) to CP1L (CP1W-CIF01) pin 2 (SD) NB pin 9 (SG) to CP1L (CP1W-CIF01) pin 9 (SG) CP1W-CIF01 Bridge between pin 4 (RS) and pin 5 (CS)

[Michael Walsh]

You need to make sure that the Baud rate matches on both sides and the following settings are made on both sides: Data bits = 7 Parity = Even Stop bits = 2 Station (NB side, right click on PLC and choose properties from the Config and setup window) = 0 Unit No (PLC side) = 0

[ct8356]

Thanks Michael. Good advice. The final piece of the jigsaw puzzle was one of the DIP switches on the PLC. I think it is DIP switch number 5, it controls whether the serial port should use Auto connect, or something specified by the HMI program. We switched it to NOT Auto, and now it works nicely.

[Michael Walsh]

Yes, that dip switch will make the baud rate, parity, stop bits and protocol be set to the default protocol (as opposed to being configured and downloaded by CX-Programmer). The default for an NB program is 9600, 7, E and 2 (Host Link), which is also the default settings for the CP1 communication port. Both sides could be modified to other values (faster baud for instance) as long as they both match.