RS232 in FX3U

[Giannis 0]

Hi everyone, I am using an FX3U PLC with the FX3U-232ADP module and i'm trying to make it talk to a PC. I am using the GX IEC developer version 7. For starters i tryed to send a couple of words with the following program: I thought it would be pretty straighforward but i cannot get it to happen. Flag M8122 is suppose to clear itself once the trasmition is complete (and it does) but i cannot get data at the PC end. I have tryed both with hyperterminal and a VB prog (both tested with another pc and they work fine). The strangest thing is that when i transmit a character from hyper terminal to the PLC, i get "fx" back for no reason at all. It even does it when the PLC is in stop mode. Can anyone tell me if there's something wrong with my code? FX3U is suppose to be very similar to FX2, so any ideas should be appreciated. Thanks in Advance Giannis

[Guest aprendis]

1.pdf Hi!! In mexico is not available the GX IEC DEVELOPER 7.0. however i read that this version is uncompatible with the fx3u, check it. check the cable too, i attach the diagramm. If you want to read the fx3u communication manual, you can download it in http://www.lp-elteknik.dk/sw3958.asp

[Giannis 0]

Hi, aprendis, Thanks for your reply I have already solved the problem. I'll try to expain the bug of FX3 just in case someone comes across the same problem. FX3U has the potential of working with two independend RS232 Channels. That means you can either put two FX3U-232DP modules, or one module and the RS232 programming module FX3U-232-BD (which on runtime can be used as a normal RS232 comms port. In the manual it sais that when you use the FX3U-232-BD, channel one is automatically allocated to it, whereas when you use two FX3U-232DP, channel one is allocated to the module nearest to the PLC and channel two to the remaining module. I was using one FX3U-232DP module and a FX3U-USB-BD and i thought that channel one would be allocated to the RS232 module, but i was wrong. For some reason the FX3U-USB-BD occupies channel one and leaves only channel two available. So all you have to do, is use the RS2 command instead of the RS command and adress data to channel two, right? WRONG !!! The IEC Developer Version 7 has a small bug in the RS2 command. When you use Ladder diagram, the Input for defining the amount of the received data appears as an ouput and the developer won't let you write to it. So what has to be done is to assign a register to it and let it read from there. After doing all this i managed to make it work. It hasn't given me any more trouble and i hope that's the way it stays. I have to use the Analog module in the next days, i hope it goes smoother Hope that i saved someone the frustration that i been through