Rockwell AOI for Modbus Client Adressing?

[harjeff]

I am trying to connect to a Chiller through Modbus TCP that has been setup as a Modbus slave and I see the Rockwell AOI and it looks pretty straightforward for connecting. The question I have is in the Data tags in Control Logix that get auto created Like Client_01_Data.HoldRegisters_4xxx[0] - Client_Data.HoldRegisters.4xxx[1023] are the array tags. The Chiller Manufacturer provided the tag mapping for their system, but they are in storage locations 401201:401202, etc. I am assuming I need to access 1207 and 1208 to get my data I need to display in the Rockwell PLC, but the array only goes up to 1023? I my missing something here? How would I access addresses above 1023? I haven't actually tried to connect yet as the system is still being built and sent to our facility, but I am trying to setup my program prior to arrival.

 

[Contr_Conn]

When Client AOI brings data back to the controller, it places it based on the LocalAddress value.
You can specify any LocalAddress between 0 an 1023

For your example of addresses 401207/401208, AIO client settings will be:
Begin Address 1206
Count 2
LocalAddress 6
The data will be in Client_01_Data.HoldRegisters.4xxx[6] and Client_01_Data.HoldRegisters.4xxx[7]

 

[Contr_Conn]

Also, pay attention to the Station ID.
Default is 0. Based on your Slave device it also can be any number 0-255. Values over 127 will be shown as negative unless you have them in HEX

 

[harjeff]

OK, Thank You, that makes sense to setup the transaction with higher start address to accommodate my range.

 

[Contr_Conn]

OK, Thank You, that makes sense to setup the transaction with higher start address to accommodate my range.

I guess you mean "Higher LocalAddress" - if so then it should be any between 0 and 1023.
The BeginAddress value dictated by the Slave and can't be changed

 

[harjeff]

What I was saying was

Begin Adress in the transaction I can set to 1000 with a count of 350 and Local Address of 0

Then I would be able to see registers 401000 - 401350 in the Modbus Slave PLC with Registers Client_01_Data.HoldRegisters_4xxx[0] -Client_01_Data.HoldRegisters_4xxx[350]

Those values encapsulate the range I need to see from the Rockwell PLC to the Modbus Slave PLC in the Chiller.

 

[Contr_Conn]

There is a transaction Count limit of 120 registers.
Everything else is correct.

 

[harjeff]

Thanks Again, The AOI has 5 built in transactions, so I guess I just use the other transactions to get all the addresses I need.