Idec Plc mobus communications

Thanks to all for the help in the past!!

I am using a Idec PLC model FC5A-D16RS1 with a FC4A-HPC3 Rs-485 module. I want to control the start/stop functions of two Mitsubishi F700 VFD's through Modbus-RTU. I have included the drive manual pages for review. It looks to me that register 40009 is the "control input instruction" the table in the middle is a where bit 1 is the forward command.

This is where I need some help. The Idec support says to use a move command to read and write to registers. What does the ladder look like to set 40009 and start the VFD.

Thanks in advance for the help!!!

I wish I could be of more help, but I don't know much about the Mitsubishi.

I will share this: All the modbus functions can be handled automatically by the IDEC pentra if you simply set them up in the "function area settings".

Your drive must be set up with a matching address. Your function settings in the Pentra will assign the "set coil" function to a code that the drive will recognize as a "run" command, possibly the 40009 you mention. When you turn on the coil in the pentra.... that you have defined in the function area...... the pentra will schedule and execute the modbus function required to "set the coil" in the drive.... if you do the set-up properly, the coil for "run", or "forward".

Sorry I can't help you more.

Stationmaster

Thanks, I will try it once I get the two to communicate. Still battling that.

So do I use function 05 to force coil 40009 in the VFD? Or do I use function 06 to preset single register 40009?

In My application I had to use 1.???? to force a bit. Like 1.2113 to force that bit in an Direct Logix PLC. (OCTAL). I could use 2.???? to read the status of an input. I could use 3.????? for a register or 4.?????. Thing is on some of the units (not all were PLCs) the 4s did not work. What I found was I had to use a 3.???? in that case because of a compatability issue. (the vendor of the one of the units told me this) I remeber seeing the 5 and 6 in documentation but it did not apply to my app so I cant help on that. So it looks like 40009 is a 16 bit register. You might have to set bits 0 and 1 or 2 depending on direction as well as give it a speed in 40014 (depending on how it is configured for speed?). 40014 would require a value written to it as opposed to 40009 a bit set. Setting a value in 40009 could get crazy!

So I would write 010000000000000 to register 40009 for forward and 1000000000000000 to 40009 to stop? The speed is controlled by drive PID.

No if you do that you will turn off all the bits in the register except the bit where the 1 is and it is the bit 14 and 15 not 0 and 1. Remember if you write to the register you need to be careful about the other bits in that same register. If you write to the bit it will only effect that bit.