Thread Starter


<P>Here is a scenario </P>

AB PLC unit with Flex I/O<BR>

RECEIVER 2------------HUB-----------RECEIVER 1

<P>To avoid accidental situation that both Receivers and Feeder will try to go to HUB at the same time they have to notify each other of their movements. If BTR and BTW instruction is used. what info should be send? </P>

<P>There are two signal created RECEIVE 1 _HOME , RECEIVER 2_ HOME. and FEEDER _HOME</P>

<P>HOME means opposite side to HUB. and only at that point in time one of them can move towards HUB. Logics of it is simple but what info had to be send. Just these three signals to main processor, which is at FEEDER. Or all I/O signals? At which point? This is a very slow process. My first project assignment I did involved only a processor with its own I/O but this is a new to me with this remote I/O using RIO communication system.</P>

<P>Can you help?!</P>
Hi Tad! I don't understand why you need to put a hub in between, to connect the two flex IOs, when you can connect it directly to the PLC using RIO connection. I had just finished commissioning one plant with a PLC 5/40 and 15 flex IOs as the RIO and it worked fine (using ASB on all flex IOS). Adding a hub in between will not affect the polling (slow as you said). Unless you are in the edge of the total length of the cable, or you have problems with the cabling.
<P>Why are you using a hub ?</P>

<P>should your layout not be as follows</P>
Scanner card
FLEX i/o --------|
ASB -------------------------------FLEX i/o


Larry Lawver


I can't understand your question, even though you went to some admirable effort to post it.

Most SLC500 systems using RIO and FLEX I/O don't need to use BTR and BTW to handle discrete signals.

Does your sketch show your cable routing or a machine diagram? If it's a cable routing, it's inappropriate for Allen-Bradley Remote I/O, as
someone else has mentioned. Are you perhaps trying to use Ethernet/IP I/O? There is no such thing as a hub in RIO, all cable runs are daisy-chained.

In a SLC500 system, discrete FLEX I/O on RIO is normally attached to a 1794-ASB RIO Adaptor, which is connected by Belden 9463 cable ("blue
hose") to a 1747-SN RIO Scanner in the same rack system as the SLC500 processor.

The I/O points are mapped directly into SLC500 data table space, without block transfers.

I suspect that you are just new to the terminology, and are trying to describe machine operation rather than signal flow. I suspect that you have a simple I/O mapping problem, and don't need BTR and BTW at all.

Post more details, and this forum will do all it can for you!

Hope this helps!

Larry Lawver
Rexel / Central Florida