DF1 Protocol

[YoungWint]

Guys/ Gals

Have an application where I am using DF1 protocol on a compactlogix to communicate with a radio device.

The plan is to read date (no write) from the PLC to a SCADA/ RTs system via the radio link.

From the users manual I have set my comm port as recommended and set up three arrays of 255 (2 x Integer, 1 x Real). These have all been declared a PLC5/ SLC for data mapping.

The interface to the Radio link is a hardwired DF1 with, I believe the transmitter set accordingly. The gap in my knowledge, and information, is if I need to write my data using MSG to the radio link or not !! Or as would seem logical the SCADA system drills in and retrieves its data from the specified files.

SCADA and the actual Radio Link is being done by a third party with the radio system being Churchill (new system to myself).

At this stage any advice or knowledge would be greatly appreciated.

Cheers
Young Wint

 

[Ken Roach]

In general, SCADA systems initiate requests to remote controllers (like your CompactLogix) and you don't need to program a MSG instruction to transfer that data.

One detail that frequently comes up is the error checking mechanism; if Churchill designed their software around the SLC/MicroLogix family they will have used CRC error checking, while the default for the ControlLogix and CompactLogix is BCC error checking. All you have to do is change that setting in the CompactLogix port configuration.