I have a PLC5 Program that I have converted to a ControlLogix. There is one PLC2 Unprotected Message read from PLC2 Address zero "0". The ControlLogix Message Read Configuration will not allow me to enter an address of zero "0". I get an error "Invalid Remote Element for PLC2 Message Type". Has any one seen this one? These message instructions are reading from and writing to K-Tron feeders. I am still waiting for a response from Rockwell/K-Tron and I am not familiar with the PLC2 Data Table.

 

I assume you are talking about the node address on the Data Highway. Over the years I have experienced a number of strange behaviors when trying to interact with DH nodes numbered less than 10 octal. Since the DH hardware was designed originally to be used with PLCs (built in 1980) that were programmed with terminals which could not enter an address lower than 10 there was no issue. It has become one only since we are creating messages on computers and newer hardware. Just set the address higher and the problem will go away.

Oh, and just in case you are talking about a data table address. The same restriction applies. The first digit defined 0 = Output Image Table, 1 = Input Image Table, the second digit defined the rack (and racks were numbered 1 to 7) - there was no rack 0, so that's why the lowest word number that could be entered was 010. Remembering all this all of a sudden I feel old. Of course over the years as various firms created "DH Compatible" equipment they sometimes misunderstand the restrictions. It's been a good source of employment.

Hugo

 

Another method is to convert your K-Tron electronics over to ControlLogix. We specialize in LIW (gravimetric) retrofits, and can supply a complete system that will easily communicate with your PLC. Please review our website www.MelfiTechnologies.com and click MELFI FEED for a K-Tron retrofit case history.

We can assist you in the conversion to conventional analog loadcells, or can supply a serial interface to directly read their proprietary loadcell.

Regards, Delmar Schmidt
Melfi Technologies Houston
Phone/Fax 281-259-3766
Cell/Mobile 281-389-6211
[email protected]