PLC coordination function on AB DH+ network


Thread Starter

Alex Wei

Is there anybody know how to implement a PLC coordination function on the Allen Bradley DH+ network. I try to use one coordination A-B SLC 5/04 as a coordinator to accept request from PC, and to assign missions to several equipment (Shuttle, Cranes) for material handling transportation, those all control by Allen Bradley PLC 5 or SLC 500 and link on the DH+. Is there any third party product can help to assign the mission without using BASIC module for ASCII string transmission between PLC and PC ?

Steve Burbrink

Talking native DH+ is the best bet. Trying use RS-Linx an Visual Basic or something similar.
You can use Ch0 in user mode and use the SLC ASCII instruction set to implement an ASCII protocoll stack. The ASCII functions are not as powerful as a high level language as C but they are quite ok to implement simple protocols.

Cheers Rolf
RG Electrical Engineering & Consulting
2 Little Street, Fannie Bay NT 0820
PO Box 37601, Winnellie NT 0821
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Allen Bradley System Integrator
Rockwell Strategic Software Provider
You could use a Visual Basic program and one of the many A-B Active X controls on the market, such as Cimquest or Automated Solutions.

It would work very well, especially under NT. But you should have some programming experience, or at least be very willing to learn.

I tried to use VB 6 and ActiveX control driver from INGEAR to interface with the PLC thru CH0, the transmittion is ok for connecting with one PLC, after connect thru the DH+, the VB program seems got conflict on the multi-timer and give an error, the program trip out right away (run under Windows NT 4.0) I exam the VB program cannot find any bug, looks like the OS cannot handle multitask timer in one program. That why I give up using VB and instead try to find another solution.

Mike Johnson

Have you tried to use VB 6 with OPC implementation. I think with using OPC you can setup OPC paths to each PLC on your AB network through RSLinx OPC server option. Hence, you should be able to pass data from the PC to all
the PLCs on the network via OPC communications. The OPC foundation website
( ) has all the documents and "classes" needed to achieve this goal. Just look under downloads then specification, and you
get access to the latest and greatest revisions of OPC specs.
CTC Parker Automation has MMI products which also are PC's. Depending on modules purchased this device could run the whole show for you.