› PLCGurus.NET Live & Interactive Forum › PLC Questions and Answers › Rockwell, Allen-Bradley, Stratix › 1794-IR8 Configuration
Hello everyone. I have installed a remote Flex i/o enclosure with a AENTR ethernet adapter and an 1794-IR8 RTD card. I have landed 4 Rtd’s on this card. The RTD’s are 3 wire PT100’s with a Fahrenheit range of -58 – 572. I have tried using an AOI scale block and tried using some other scaling methods we have and nothing seems to work. I have tried reading the 1794-IR8 manual, but it’s not very helpful (To me anyways). Is there certain config bits on this card that need to be set? I have never used one of these cards before. Any thoughts or ideas? Anything would be appreciated.
Did you send the three configuration words?
No. I did not. I did read in the manual about a BTR and BTW block, but I thought that was if you were using PLC 5 or older. How do you send the words?
What PLC are you using? Did you try to reset power to the module? Do you have any kind of fault on the module?
If you are on ControlLogix or CompactLogix, when you added the card to the IO tree, it should have given you the configure options. You do have it set up in the IO tree?
Attached example config
Yes. Mine is a 1794-ir8 though. The Flex i/o is remote to an L83ES ControlLogix
Are you getting any readings at all, and just can’t scale them, or is the data all zeros. You have DC Common on terminal 16 row b and +24 VDC on terminal 34 of row C. Any fault bits on the card, or over/under range.
Over range alarms. On all channels that are wired. Yes, the DC common is on terminal 16 on row b and +24 is on 34 of row c. If row b is common all the way across, do the rtn commons have to be on a particular terminal? I know the manual has a specific terminal for each channel, but these are all jumped together in the terminal box in the field and brought back to the common (row b). That doesn’t seem right to me
Do you have 2 or 3 wire RTDs? If 2 wire, make sure to jumper the signal return to the low side terminal (Look at the table on page 2-6)
Sorry for the delayed response. I believe its sorted out now. There was a wiring issue.
OK good. Glad you got it sorted out.
I was going to say – the last time I worked with one of these the way the wiring is connected – was a bit strange on the 3 wire .. can’t remember the exact detail anymore – the manual was not exactly clear on the subject.
Looks like a few Tempsonics in that project as well .. Nice units..