Communication between VB and Allen Bradley PLC

Chiefsta

Member
Join Date
Nov 2006
Location
Port Elizabeth
Posts
1
Hi ALL,

Could any please help. I have a Allen Bradley PLC (500)that has a RS 232 port and would like to read and write to various registers using a Visual Basic Application. How would i go about doing this?

I already established a link from my PC to the PLC using the RS232 comms port available using RS links. What options do i have to link between the two (Visual Basic and the Allen Bradley PLC) and how would i achieve this? Do i need write a protocol or is one available?

My ultimate goal is to display and write values of the registers to the PC screen using VB.

Please Help:sick:
 
Search your manuals or AB's website for the documentation... it's been several years since I've done that, but can tell you it's possible and the VB programming interface is documented. You can also manipulate RS Logix from VB (one of my programs opened RS Logix, downloaded program, and e-mailed me if a tech changed the program. Also made PLC backups daily). I've seen "reads" from an Excel spreadsheet as well... I'd assume you could write too. Excel supports VB script. Again, search for some docs.

Justin
 
RSLinx is the key

You can use RSLinx via the DDE/OPC server function and VBA code to "Poke" data into areas such as interger files etc.

Ken
 
If you want to use the DDE you will need an RSLinx that allows you to connect to the topics (ie. Pro or Gateway).
In VB6 the way I have done it is with text boxes for example:

Text1.LinkTopic = "rslinx|mytopic"
Text1.LinkItem = "N7:0"
Text1.LinkMode = 1
Text1.LinkRequest or .Linkpoke


The mytopic is setup in RSlinx (configure DDE/OPC topic). The item is your address. The link mode is how you want to connect (manual, auto, none). Request pulls from the PLC and Poke pushs to the PLC.

I am trying to use the vHMI on a Compact Logix now but I'm having problems getting it to read properly it is only $50 as opposed to the thousands for RSlinx (probably spent thousands in time to figure it out though).
 
I wouldn't even use RSLinx in this case. Perfect application for Archie's Open Source AB DF1 project.

http://www.plctalk.net/qanda/showthread.php?t=41293
http://sourceforge.net/projects/abdf1/

Chiefsta said:
Hi ALL,

Could any please help. I have a Allen Bradley PLC (500)that has a RS 232 port and would like to read and write to various registers using a Visual Basic Application. How would i go about doing this?

I already established a link from my PC to the PLC using the RS232 comms port available using RS links. What options do i have to link between the two (Visual Basic and the Allen Bradley PLC) and how would i achieve this? Do i need write a protocol or is one available?

My ultimate goal is to display and write values of the registers to the PC screen using VB.

Please Help:sick:
 

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