A/B-1762-L40BWA FRN 11 & MODBUS Help !!

[Chip]

Hi, All

Trying to configure A/B MicroLogix 1200, 1762-L40BWA FRN 11 & ModBus, Have a Link to the Manual's.

Hear:  http://www.ab.com/programmablecontrol/plc/micrologix1200/downloads.html

This manual section E ModBus info: http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1762-rm001_-en-p.pdf

Just VERY Lost at this Moment I Hope, Have updated the PLC to FRN 11 needs ver 8 or above to run modbus.

Set it to Modbus RTU Protocol "Master", It set's it to "Off line", Just Power Light on, RSLogix500 software.

Com 2 port set, ModBus test on/off "no errors", Reading states timmed out.

Thanks, Chip

[Peter Homann]

Hi Chip,

I would expect that the PLC should be set to RTU  Slave mode. Mach3 is the Master.

Cheers,

Peter.

[Chip]

Hi, Peter

I'll try that again, Had it set that way once, But not set to "Off line", Just Power Light on Mode.

Getting an Illegal Data Value now so it must be talking at least, Progress !!!, Thanks Peter !!!

Need some examples on opening and closing a coil input and output, Or something other than "Illegal Data Value".

Just Stumbling Around Hear, Chip

[Chip]

Hi, All

First time trying to interface a PLC to Mach3 ModBus, It's a A/B MicroLogix 1200, 1762-L40BWA FRN 11 .

It's talking to ModBus, But all I'm seeing is "Illegal Data Value", or "Illegal Function" on Mach3 ModBus Status: window/Line.

Using  RSLogix500 software with proper ver. for ModBus, Set to 1200 Ser. C, Bul: 1762.

OK: Duuuu Question, Dose the Ladder Logic have to be setup in the PLC before setting it nto ModBus Mode.

Any one have a Solution.

Thanks, Chip

[Peter Homann]

Hi Chip,

The Modbus Master (Mach3) requests writes to and reads from registers in the PLC.

For this to work, You need to

set up the registers in the PLC
Write ladder logic to interact with the PLC registers
Set up Mach to read/write the registers set up.

Errors in any of the above steps will cause it not to work. Does the PLC come with a tutorial or quick start guide?

What you may want to do initially, is write some ladder logic that just takes the value in a a few coil registers and sets the output on the PLC, Then get Mach to set the coils. If you set the Mach outputs to these coils it should be a simple test.

BTW, I don't have a PLC myself.

Cheers,

Peter.

[Chip]

Hi, Peter

This PLC has 24 Coils "0", 16 Contacts "1"

Need to now "Size (# of words)" (default is 1 Integer Words), or option, Binary Words. Is the default value Proper ?

It's also asking for # of Input Register's "3" and Holding Register's "4" and there word length, Haven't found them in the A/B spec. sheets 

Do you have any idea on these.

Thanks, Chip

[Chip]

Hi, All

Illya on the Yahoo group sent a ModBus ModSlave.RSS file for the 1200 seres A/B PLC.

The file got me going, A little editing to do for inputs/outputs at some point. But I can read & write to the Plc now, Still unsure about proper start

addresses to turn on an output or see an input though and using the Input Register's and Holding Register's.

Have the online manuals for Ref., Lot's to Digest though.

Thanks, Chip