FX3U Modbus communication

[kaare_t 155]

What about 40201, 40202 and so on? These are the realtime variables... I will have to check the writing command tomorrow...

[pinguinjkeke 3]

201 and 202 returning 0

[kaare_t 155]

That is correct since the inverter is not running (201 = Running Frequency and 202 = Running Current). When it comes to writing the manual has some nice examples of writing. Just try to set the setpoint frequency, then start the inverter using bits in words. Just remember to check which function code the inverter supports (not sure if it supports "Write single register", maybe you need to use "Write Multiple Registers" - you can still define only one register even if using "Multiple Registers")

[pinguinjkeke 3]

Hello again. I successfully read 201 register and tried to write 102, 104 parameters and it's successfull!. But I can't read and write to system environment variables 40002-40015. I still getting 212 modbus error. Tried both write commands H6 and H10. Don't know what to do with it

[kaare_t 155]

I think I've might mislead you, I'm not sure if 40002-40015 are readable/writeable. I think you must use all the other parameters, so maybe this is correct... I don't have an inverter to test on right now so I'm not sure, but you should be able to start/stop and sett speed on the inverter from the other parameters...

[Guardian 0]

Hi, I'm new in FX3U programing. I'm trying to build a simple application connecting a PC to a FX3U plc using LabView. I'm trying to follow this application note : http://www.ni.com/white-paper/13911/en/ I have a FX-USB-AW adapter and a FX3U-232-BD adapter. I can easily communicate with GX Developer software using both adapters. Can I implement MODBUS over RS232C with any one of these adaptors?

[kaare_t 155]

Which PLC software are you using, and what language in the software are you using?

[Guardian 0]

I'm using GX IEC Developer v7.01 and Ladder language. The PLC is the FX3U-16M.

[kaare_t 155]

That will not be a problem as there is finished function blocks for that purpose using the FX3U-232-BD adapter. Are you going to be a slave or a master in the PLC and I will upload the files to you.<br><br>EDIT: FYI Mitsu also has the FBs in their site if you'd rather download them there.<br> Edited 14 Mar 2014 by kaare_t

[Guardian 0]

Thank you kaare_t !!! I was looking for FB in the last 2 days. I only have found the FB for the FX2N plc. I tried to used them, but the memory/registers and the logic are different. I want have the plc as slave.

[kaare_t 155]

Use this. The example might be FX2N (don't remember), but the block works on FX3U. Let us know if you run into problems. ModbusFXSlave_V100.zip

[Guardian 0]

Hi kaare_t, First of all I should say thank you! I found a program demo for slave PLC in meau.uk. In the first times it worked well. I communicated with PLC through RS232C with Labview and GX IEC software. Then I started to build the final application program and the communication failed. Now I started from the scratch again and it is not working. In the process I probably latched some register and now it is not working. I get the general error "ES:0180840b"... I'm not able to communicate with using Labview or GX IEC, but the Modbus Tools software ( http://www.modbustools.com/ ) works perfect... When I try to connect using GX IEC the RD flashes but there ir no answer! Could be something related with this? http://forums.mrplc.com/index.php?showtopic=26698 Do you have any possible cause/solution for my problem? That you in advance!

[kaare_t 155]

Are you connected to the programming port or to the BD card? Remember that after setting the BD card to Modbus (NoProtocol), you must use this on the port. Use the programming port for GX IEC etc. Let us know what you use, and how you plan to use it...