Allen-Bradley 1746-BAS with Modbus


Thread Starter

Luis Paulo

I am using 1746-BAS Module without EPROM Modbus and I need create all protocol Modbus in basic (not VB) to communicate with Yokogawa Transducer, someone can help me?


Bob Peterson

I have actually written BASIC code (not VB) that implements some Modbus master functions, I only implemented them for Modbus ASCII and only some functions (register read and write).

I found it impractical to implement RTU or slave functions in BASIC. Just too convoluted and very slow.

I can assure you that buying the Prosoft module is well worth the cost and suggest you do so, and not even try to do this with a 1746-BAS.

Some time ago I think I posted the code I had written for the Modbus ASCII functions. You might be able to find them stored in the Automation list archives. BUT, you are far better to just buy the Prosoft module.

Bob Peterson
I believe the Prosoft module to which Bob is referring is a VAR'd 1746-BAS fitted with a Modbus PROM, either master or slave. If so, it would be worthwhile to ask Prosoft if they will sell the PROM by itself or let you send your 1746-BAS to them for modification.


Rajesh Agravat


It is possible to read the modbus data using BAS but it is not advisable to make programming for all the modbus functionality, because it requires Lotof work in Logix also. and finaly it will slow down your update rate.

Actually 1746-bas is designed for programming the application specific requirement

Rajesh Agravat

Mark T. - ProSoft Technology Inc.

ProSoft Technology does not sell the EEPROM stand-alone. The 3150-MCM Modbus module for the SLC platform is sold as a complete unit. The orignal ProSoft Modbus unit was sold as a EEPROM for installation onto a 1746-BAS module.