3150-MCM Slave Port Configuration with SLC 5/04 (Strange)

Hi,

Attach is the program for one of my developing system, which consists of 3150-MCM in the last slot (11). I've not configured any Slave port for 3150-MCM beforee.

I'm only using the Port 1 of te 3150-MCM & being configured into Slave. It'll be communicating with a Master (DCS).

I'm pulling/writing the data using ModScan32 as I do not have DCS in my office.

When I configure the word count (N10:54 & N10:64) to 10 words, it's suppose to update 10 words, but in my program it's updating more than 10 words! Same goes to Read & Write Block.

Is it because this is slave and I cannot limit the words count? or disabling the entire command?

Hope some can enlight me

Thx in advance.

If you configure your port as a master then your modbus command list starts from N10:50. The word count that you are specifying in N10:54 and N10:64 will only be used if you are using the port as a master.
Since you have configured port 1 as a slave, the command list is basically of no use.
Also, in rung 1 of ladder 3, the branches where you are comparing the value in M0:11.0 to 80 and 81 are not required.

ashley said:

If you configure your port as a master then your modbus command list starts from N10:50. The word count that you are specifying in N10:54 and N10:64 will only be used if you are using the port as a master.
Since you have configured port 1 as a slave, the command list is basically of no use.
Also, in rung 1 of ladder 3, the branches where you are comparing the value in M0:11.0 to 80 and 81 are not required.

Click to expand...

Hi,

Thx for ur reply, so this means the slave do not have the ability to specify the number of word count (Command list not use). Thus the number of read or write block is depends on the LENGTH in the COP instruction (50 in this case), am I right?

Thx.

That's right

ashley said:

That's right

Click to expand...

Ashley, appreciate for your help

Thx a lot.