writting commands on GE MM300 using code function 16

[elhaimer 1]

The communication is between micrologix 1100 and GE power relay MM300, I have the following informations : performing function.bmp And the command adress is as followed : command adress.bmp And I want to write one of the following commands : commands.bmp But the problem is with the packet format, and that`t what i perform but does not work : performed.bmp Thank you in advance for your help !

[rootboy 1]

Get yourself a Modbus monitoring program such as: http://www.simplymodbus.ca/RTUslave.htm or: http://www.modbustools.com/download.asp (or try out one of the free ones) and use that to debug your connection. If you are still having problems, paste a few examples of what you are sending out of the PLC with the coresponding results as seen by your Modbus monitoring program. While working for Schneider I had the opportunity to interface several different devices to our ION meters, and the typical "Failure Mode" was: a) The physical connection (this is where com adapters that have blinky lights are a big help. I recommend this one: http://www.usconverters.com/index.php?main_page=product_info&cPath=75&products_id=280). b) The target's interpretation of the Modbus spec (and arguably Schneider's as well). By breaking the problem down into halves, you get to see what you are transmitting, and if you get the Modbus Master as well as the Slave, you can try out different messages to the GE relay to see what works for it. Here's an article concerning memory mapping (and endianess): http://www.controldesign.com/articles/2010/ModbusDevicesINQ110.html We had problems with a steam meter until we figured out that while the documentation said register 4001, it really wanted 40001. Be sure to try this as well. And don't forget the age-old Modbus conundrum of whether the register 4001 is mapped to 4001, or 4000 (some implementations of Modbus start at one, some at zero). If 4000 is the case, you will have to offset everything down by 1. Edited 18 Aug 2013 by rootboy

[elhaimer 1]

Thank you rootboy for your help ! the problem is more than this and i have no problem with the physical connection neither with the adress mapping (all you said about it is right), And all I want to know is how can I configure my MSG file with the writting function code 16. I wish you understand my problem !