PLC5 Analogue IO addressing

Hi all

Have mostly worked the SLC500 family of AB products but have recently had to look at a old PLC5 unit.

It appeared to me that the analogue input cards were mapped directly to a N14 data file.

Now I know that you can create new data files but how can you address your IO to a N14 register without coming in through the I1 input data file?

Thanks

Look in the program for a BTR, Block Transfer Read, that places the integer from the analog card in Rack x slot x to the N register.

Take a look at this: http://www.patchn.com/plc_analog.pdf

With the 5's when you install a new rack, input and output words are assigned for each slot. Which slot addressing scheme you use will determine the number of words per slot, but it is usually only one or two words. Not enough for an 8 channel analog card.

So you have to use BTW & BTR with what AB calls intelligent I/O.
BTW & BTR are usually in pairs, the BTW is required to "setup" the card, the words transferred from the PLC to the card determine, scaling, BCD or decimal etc....
The BTR is used to transfer the card information to a plc memory location, the the plc can use these values in the rest of the program.

The same technique can be use with Later model SLC's (series C), and remote analog I/O.

Ron and Ken

Thanks very much for your replies, very helpful

In addition to what Ken has mentioned, BTW is also used to write the analogue value of the output module, this is beside it is used for the card set up(e.g scaling, volts, mA, broken wire detection..etc)