Applies To:
  • CitectSCADA 5.xx

I am using the ABRSLINX driver to communicate via RSLinx to a ControlLogix processor. How do I read a DINT (double INT) value from the processor? Why does the driver not support the standard RSLogix "L" data type?  

The ABRSLINX driver connects to RSLinx (via an API) and reads data using standard functions supplied by the RSLinx Software Development Kit (SDK). These functions support numeric based addressing and must access data in the ControlLogix via mapped PLC5 compatible messaging. They cannot access data using the ControlLogix "native" tag addressing scheme.

As there is no data item 'L' in a PLC5, reading DINTs is not supported. Therefore you must map the DINT to a valid PLC5 data type like a FLOAT or use a INT for the source tag. The ABRSLINX driver v1.02.01.000 or later, can also support reading a LONG from two consecutive INT addresses.

An alternate option is to use a driver that supports ControlLogix "native" addressing - currently the Citect OPC driver supports this. See also Citect KB article Q3424 for a discussion of the different protocols for Allen Bradley equipment and compatible Citect drivers.