1771-ASB Good or No good such a ?

Hi Guys,

I'm trying to figure out if a 1771-ASB (RIO Adapter) is good or not.

Using a 12 slot PLC-5 chassis.
Backplane SW=2 & 5 ON, all others OFF.

1771-ASB
SW1= All ON
SW2-1 & 4 ON all others OFF.

using blue hose with a term. resistor to a known good 1791-16AC (Grinder).

1771-ASB:
Active Light- Solid
Fault Light-Flashing (meaning module is in the wrong slot) It's in slot all the way at the left of the rack.
I/O Rack Fault- OFF

I've read a bunch of posts about this module and am afeared this may be an ungood unit. That would be a bummer.

Any ideas? Forward Thanks

using blue hose with a term. resistor to a known good 1791-16AC (Grinder).

Click to expand...

something's not right with that part of your description ...

the 1771-ASB is an ADAPTOR - not a SCANNER ...
the 1791-16AC is also an ADAPTOR - not a SCANNER ...

those two pieces of the puzzle are probably "daisy-chained" on the Blue Hose - and they both are intended to "report" TO and "get their directions" FROM some other piece of the puzzle ... somewhere hooked to the Blue Hose should be ANOTHER piece (whatever it is) and that's going to be the SCANNER/BOSS of the Remote I/O link ... (that's usually a PLC-5 processor) ...

can you give us more detail? ... such as - what is the PROCESSOR (the brain part) of the system? ...

did the system "used to work" and now it won't? ...

just GUESSING here - but are you trying to "bench check" the 1771-ASB module - without using a PLC-5 processor (etc.) to communicate with it? ... if so - then (according to what you've posted so far) you have two SLAVES connected to each other - but no MASTER connected to tell the slaves what to do ... and again IF that's your situation, then this system can't work at all ...

Presuming the RIO Scanner is a PLC-5...

The flashing ADAPTER FAULT Indicator denotes an I/O module placement fault.

Did you just replace the chassis or any of the I/O modules?

...about your DIP switches configuration...

The Chassis is configured for 1-slot addressing- the CPU addresses one I/O module as one I/O group; this means that you cannot use 32-point I/O modules unless the the entire rack consists of pairs of Input and Output modules starting with Slot 0; if you cannot pair the Input and Output modules the slot to the right of a 32 point I/O module needs to be left empty.
Consequently, 32 point I/O modules need 32 input or 32 output bits in the processor’s image table. Because only 16 input and 16 output bits are available for each I/O group, to address a 32-point I/O module, the remote I/O adapter module uses the unused input or output word associated with the adjacent I/O slot.

The RIO Adapter is configured as Logical Rack 00 (quite unusual unless the CPU Main chassis contains only non I/O modules)

1771-ASB S2 Switch 4 ON means that the last four slots of the chassis are not being scanned; do you have any modules within said slots?

Yes, indeed!

I'm trying to do the impossible. Thank y'all for confirming the obvious!

No, I'm tasked with determining IF the 1771-ASB is good or no good. If no good then making it good.
The system was working before I stuck that module therein.

The system has a working PLC-5/40 but there is no other place for the -ASB that I can see but the left most slot in the chassis. I couldn't figure how that would work, but I certainly don't know much about these things.

Where, pray tell, would a person slot the -ASB for functionality?

I'm mostly blind and dumb, but I can count to 20 and like a broken clock am right if observed at the opportune moment.

Where, pray tell, would a person slot the -ASB for functionality?

Click to expand...

the easiest way is to have TWO working chassis - one for the PROCESSOR - and the other for the ASB ADAPTOR ...

the PROCESSOR has to go into the left-most slot ...

and ...

so does the ASB Adapter module ...

so ...

TWO chassis ...

or ...

IF you have a ControlLogix system with a 1756-DHRIO module, we could probably make that work ....

Thanks, Ron,

I looked for a -DHRIO, but got the goose egg on that one.

I'll try the two chassis config

So, please forgive me for asking.

Do I go from the PLC5/40 to the -ASB then to the Grinder with a blue hosed menagerie? or something more practical?

got your email ... this is too much to type up - but give me a call and I'll talk you through it ... should take about 10 minutes ...

we'll work on this tomorrow - but I'll go ahead and answer this basic question for you now ...

Do I go from the PLC5/40 to the -ASB then to the Grinder with a blue hosed menagerie? or something more practical?

Click to expand...

BASICALLY -

you could go from the PLC-5/40 to the 1771-ASB through blue hose ...

or ...

you could go from the PLC-5/40 to the 1791-16AC through blue hose ...

or ...

you could go from the PLC-5/40 to the 1771-ASB - AND - to the 1791-16AC (that's BOTH of them at the same time) through blue hose ...

what you can NOT do - is go from the 1771-ASB to the 1791-16AC - while leaving the PROCESSOR completely out of the picture ... attempting to do this would end up with two "slave devices" trying to talk with each other ... that won't work ... SOMEBODY'S gotta be the boss - and that's the PROCESSOR'S job ...

the general idea is that the 1771-ASB is used to make an additional chassis serve as Remote I/O ... so - the PLC-5 processor would have LOCAL I/O modules (located in the same chassis with the processor) - and it could also have REMOTE I/O available to it - by using the input and the output modules located in the OTHER chassis - (the one with the 1771-ASB adapter) ...

the little 1791-16AC is generally called "BLOCK I/O" ... you have the equivalent of an INPUT module built into the "block" ... and you also have the equivalent of an OUTPUT module built into the "block" ... the grey piece of the puzzle in the middle (with all of the DIP switches) serves exactly the same purpose as the 1771-ASB adapter ... in simplest terms - that's a built in COMMUNICATION device ...

Ah-HAH! I see . . . said the blind man as he reach for his hammer and saw . . .