FX3G Two Channel Modbus

[Matt485 0]

Hello everyone. I'm a new comer around here, but glad to be here I have an application with a FX3G CPU setted up with 2 Modbus board FX-485 ADP and FX-232 ADP. The 485 is connected on channel 1 (CH1) as Master of a Fire alarm System , the 232 on channel 2 (CH2) is the slave of a my PC. I'm programming with a Gxworks 2 and I've already setted up everything with functions block (Master and Slave) shared from My mitsubishi website section. Everything works fine, I've the good communication between the CH1 and the fire alarm panel , and Iwas also able with a simple funciton ( BMOV) to read some bits and word coming from CH1 to CH2. I am able to read address from my PC from 0 to 125 according FX3G manual, these address are the moving of the analog input registers of my fire alarm system (start from 30001). In case of a fire event, I've received on ,my PC the reading from address 0 that in the device buffer mem of the plc is ''D0'' Device, and for real is the Modbus register 300011 that is moving from the fire alarm sys. And Here is my problem : I have the necessity also to write in a couple of Registers, but at this time are Holding registers to be more precise are regs 400001. I need to move up a couple of bits using the Modbus function ( 06 ) or also function (05) And here is my question : If PLC assign for my 300011 the device ''D0'' What is the ''D'' related to the 400001 ? Is there an easy way to discover what is the value of D connected to Register 400001 during a test ? Do i need a Sniffer ? Thanks a lot to all of you. Keep in touch.

[kaare_t 155]

When using the Slave FB, D0 = 400001 if I recall. If not, could you post a screenshot of the ladder where you've used the FB for slave? I think they are mapped automatically... I guess the Master is not a problem since you specify where you would like to store the data?

[Matt485 0]

Thanks Kaare I will post very soon the data, give the time to get back at office. You see the fire alarm panel ? You might know it its norwegian too :)

[Matt485 0]

Here is some Screen shoot The first is first scan The second is the RTU set up Label The third is the RTU set up but Device view The fourth is MDB request The fifth is Invalid MDB request- That's the slave side if you want i've got also the master side for CH1 Bye