PLC5-SLC 1746-NI4 Remote IO

Maybe someone in this forum has encountered this and could offer some suggestion.

We connected a 1746-NI4 via 1747-ASB to a PLC5/80 on Ch1B Remote I/O 57.6K speed. The 4 analog values are to be read by a BTR instruction. With the instruction XIO BT9:7/EN BTR... the EN bit gets stuck and the BTR DONE bit never gets active. Is there any Remote IO diagnostic facility in the RSLogix 5 software to enable checking where the problem is coming from? Thanks for any help.

Are you doing a BTW with the configuration words directly before the BTR? What are the conditions preceeding the Block Transfer statements? Typically, I use the "not enabled" bit of both the BTW and BTR as conditions for both.

The NI4 does not require any "setup" words, so a BTW is not needed.
Double check the rack/group settings in the SLC chassis, and the rack/group settings in the BTR. Does this remote chassis have any discrete I/O, can you confirm that the discrete I/O is up dating in the image table?

Ken Moore said:

The NI4 does not require any "setup" words, so a BTW is not needed.

Click to expand...

True...my bad.

Greetings narcilla,

and welcome to the forum ...

solving your particular problem can be quite tricky ...


if you need detailed help, please tell us EXACTLY how ALL of the 24 DIP switches on the 1747-ASB are set ... we also need to know what revision/version of 1747-ASB you’re using ...



we also need to know EXACTLY how ALL (I repeat ALL) of the modules are arranged in the remote chassis ... please use LETTERS (not numbers) for the chassis slots in order to nail this arrangement down in a totally unambiguous manner ... for example: the 1747-ASB is located in slot A ... the next module (please specify the catalog number) is located in slot B ... slot C is empty ... etc. ... etc. ... secret handshake: depending on how the DIP switches are set on the ASB, the slot numbers can actually change ... (two-slot, one-slot, half-slot addressing modes come into play here) ... you might already know about that ... no offense intended ...



finally ... the PLC-5 processor has an automatic channel configuration feature that (if everything is correctly set) should be able to “sniff” the Remote I/O network and find all of the devices out there ... let us know if you need help with this ...







if the feature tells you that you need an “I/O status file” then this picture should help ...








finally ... a super secret handshake: suppose that you’ve previously used the SLC-style chassis in a Remote I/O setup with a 1747-SN (SLC-style) Scanner module ... suppose that you’re now transferring the same “remote” chassis over to PLC-5 control ... basically just moving the cable from the SLC system to the PLC-5 system ... be aware that the blue and clear conductors at one end of the “blue-hose” must be reversed ... that’s right ... if it works right for an SLC system, then the wires must be criss-crossed for it to work right on a PLC system ... don’t ask me why ... but I’ve seen this particular dog bite several people in the past ...

Thanks for all the replies Ken, Ron and Dr. Watson. The NI4 card was actually just recently added for the purpose of reading some opacity sensor with 4-20ma outputs; the previous setup was and still working fine except for the BTR. The setup is as follows:

Remote Rack, 7-slot chassis, single slot addressing
Slot
A 1747-ASB
B 1746-IA16
C -do-
D -d0-
E 1746-OA16
F -do-
G 1746-NI4 <-- NEW CARD

1747-ASB Switch settings
SW1 3 OFF, all others ON (Rack 10)
SW2 3,7 OFF, others ON
SW3 1,4,6 OFF, others ON

Processor PLC5/80V, Ch 1B set as below:


Actual ladder



How can you decode the IO status file? Thanks in advance.

Didn't have time to check all your switch settings, but one thing that jumps out is the BTR, I may be way off base, but shouldn't it be Group 6 instead of 5?

Ken,

If you notice in the channel properties, the range of addresses for the racks that are 3/4 sized is n0-n5. The NI4 module being inserted in the last slot would then be assigned Group 5. With the 7-slot chassis, first slot is for the ASB then the next slots are for groups 0 to 5 if the starting group is set at 0.

You're correct, early in the morning, and my mind isn't fully engaged yet. Sorry for the confusion.

Turn SW3-7 off this is used to select specialty i/o mode to be either discrete or by block transfer. The default is discrete SW3-7 on.

roelandr2,

Thanks for the tip. I would try the SW3-7 OFF setting as soon as I can arrange for an eqpt shutdown.

roelandr2,

I switched S3-7 OFF but I'm still not getting a BTR/DN from Rack 10. The discrete I/O on the same rack are still all working fine. Is there any way to diagnose what's happening in a Remote I/O channel?

I'm still not getting a BTR/DN from Rack 10.

Click to expand...

that may (or may NOT) be an issue ...

due to the way that RSLogix5 updates the ladder display screen, you MIGHT not see the Done bit indicator "light up" even when everything is working fine ... the big question is this:

is the BTR bringing in the data? ...

suppose that the Done bit won't light up and that all you see are "0" values at N40:30 through N40:33 ... it might be natural to assume that the BTR isn't working at all ... but run this test ... go to N40:30 through N40:33 (four words total) and type in some "bogus/sample/dummy" values (example: "888") ...

this test will tell you whether the BTR is doing its job or not ... if the bogus values "stick/stay/remain", then the BTR is not bringing in any new data ... if the bogus values are quickly overwritten with "other" values, then the BTR instruction IS bringing in the data ... specifically, the BTR is doing all that it can do ... the next step would be to find out why the data happens to be incorrect ...

if none of this helps, you might consider posting your entire .RSP file ... we might be able to spot something that you've overlooked ...

incidentally, I think that roelandr2 hit the nail on the head with his suggestion ... assuming that everything else is correct, I'm surprised that the system isn't working OK now ...

Ron,

Thanks for your inputs. I'm aware that RSLogix is not fast enough to catch all the bits since it has a limited time to access the PLC. What I did was programmed in a XIC(BTR/DN) ONS CTU rung to see if the DN bit is really getting actuated. Counter stayed at zero.

The problem was already resolved but I'm not sure how. Just this morning we had problems with the same PLC on the DH+ (Ch1A - the RI/O is on Ch1B). The PLC can't be accessed from the DH+ link but Ch0 (Serial) works. Put PLC in Program then Run mode but no improvement. Powered down the PLC and pulled out the processor to check the card. The battery connection however got loose and had to download the latest backup. Upon powerup and restart, noticed that the DH+ and the BTR worked!

Now a question when installing new cards; do we have to restart (PROGRAM then RUN) or recycle the power (not sure which one did it) to the PLC to enable the BTR's when a new card is installed?

Thanks for all the help. Hope I could return the favor in the future.