Controllogix MSG to PLC2 DF1

[SBoily]

Hi,

On a project, we have so far been able to establshi communication between a -L63 Controllogix PLC and a Thrid Party DCS. We defined a PLC2 Tag of 6000 registers (0 - 6000)in the PLC. Then we configured the Channel 0 to its default settings wich is Point to Point, no Handshake, etc, except for station # (110).

Upon connecting the serial cable to the DCS interface, communication was good and DCS writes data in the PLC at the exact memory location that were expected. For example, date and time data are continiously updated.

The problem we have is when we want to send a Message (MSG) to the DCS. The .EN bit always stays ON and the .DN bit stays OFF. Path used is 2,0. I then used Path 1,1 to loop back the MSG in the PLC and it worked just fine. When I change the Path to "2,X", I get the .ER bit for X is not a valid address. changing the Channel 0 to master or Salve results in lost of RS-232 communication.

Why is the Contollogix unable to send a message when it accept and replies data to the DCS???

 

[Ken Roach]

What make and model of DCS system and interface module are you using ?

I have never seen a DCS interface that could accept an unsolicited MSG instruction from a controller. Every DCS interface that I have worked on (Fisher Provox, Rosemount RS3, Foxboro I/A, Honeywell TDC3000, Emerson DeltaV and Ovation) has been the originator of both read and write operations.

 

[SBoily]

What make and model of DCS system and interface module are you using ?

I have never seen a DCS interface that could accept an unsolicited MSG instruction from a controller. Every DCS interface that I have worked on (Fisher Provox, Rosemount RS3, Foxboro I/A, Honeywell TDC3000, Emerson DeltaV and Ovation) has been the originator of both read and write operations.

The DCS is an ABB SCADA using FrontEnd computers, each with 8 RS-232 channel on a Emulex Card. We want to replace a ABB "PLC" in a remote location using the existing settings to minimize the scope of work. ABB DCS Polls all the data Table in the remote PLC at Startup, but then remote PLC will update the DCS Data Table on a "Change of state" basis.

Our not so practical way to update data in the ABB system is to shut down the RS-232 link and put it on again to get the "initial" refesh...

We just found out that maybe our serial cable is not up to spec, for the RTS-CTS and DSR-DTR are not tied together. It seems the ABB doen't care but maybe it is of importance for the Controllogix.

 

[Ken Roach]

Unless you enable handshaking (it's off by default) the Logix will work fine with just TX, RX, and GND.

What protocol is the DCS using to communicate with the existing controller ?

I haven't worked with any ABB DCS systems, so I'm surprised to learn that yours is supposed to accept an unsolicited message from an A-B controller.

At this point you might need a serial intercept or a protocol analyzer. While Frontline Test Equipment is the main battle tank of serial protocol analysis, a simple two-port passthrough trick like TalTech's fantastic free serial breakout box or the inexpensive shareware Docklight might do the job.

 

[SBoily]

The protocol ABB uses is ANSI X3.28. This protocol is clearly stated in the MicroLogix 1100 manual as a Full-Duplex DF1, wich they also refer as Point to Point DF1! But it is not mentionned in the Controllogix documentation.

MicroLogix documentation also specifies that Full Duplex needs Flow Control. My best guest is to use a cable with at least RTS and CTS shorted together on the Contrologix side. Contrologix might need Flow Control even in the No handshake setting ? Or maybe with flow control on the cable I will be able to use the Full Duplex setting in the Point to Point mode.

 

[wilsonzhu]

Can you post what is your msg instruction's three tabs' setting?