1746-OV16 SLC 500 output module

ceilingwalker

Lifetime Supporting Member
ceilingwalker
Join Date
Mar 2010
Location
Phoenix, AZ
Posts
1,586
Hello all. I have an output module that I'm trying to wire-in and don't know if the module is bad or if the installer (me) has done something wrong. I went to the IO config and found my module toward the bottom. I installed it in slot 10 (only slot of 12 that was open). I found this module lying-around our shop so I'm not even certain it works. According to the drawing I found, I'm to connect my +24VDC to the "VDC" terminal and my 0VDC to the "DC Com" terminal. I have an MMI that turns on the input (not a discrete input). While online and I push the on button, the output shows that it's on, on the ladder, however, I'm getting no voltage when I put a meter on either the VDC or the DC Com, and the output terminal (O:10/1). I've never a sinker DC output board before and I'm not sure I have done it right. Anyone that could help, I sure would appreciate it. Thank you.
 
first delete the "control" in your ladder ...

then go directly to the output table and just manually change all of the output bits (O:10/0 through O:10/7) to ONEs ... all of the LEDs on the front of the module should turn ON ... if they don't, make sure you're in the RUN mode ...

once the LEDs are ON, then check the voltage between "DC COM" and "VDC" ... you should have about 24VDC ... if you don't, check your power supply and the wiring to those two terminals ...

once you've confirmed that the power is properly supplied, check between "VDC" (at the top) and each of the "output" terminals ... you should get about 24VDC ...

I'm getting no voltage when I put a meter on either the VDC or the DC Com, and the output terminal (O:10/1).
Click to expand...


survival tip: make sure that the terminal screws are all snugged down before you probe them ... in some modules (not sure about yours) the actual electrical contact is the "pad" BEHIND/UNDER the screw ... if the screws are loose, they might not be making electrical contact with the "pad" – and the outputs can look like they're "open" even though they're perfectly alright ... or ... just "go in at an angle" to make sure that your probe makes contact with the "pad" behind/under the screw ...

as I said, I'm not sure whether YOUR module falls into the design category I've mentioned above – but trust me, I've seen several cases over the years where people thought that their output modules were bad and wouldn't "turn on" because they were only probing the SCREWS and not making connection with the business-end of the output circuits ... (GOTCHA!) ... this is especially common once the module has been USED (as you said yours has been) – and the screws were left loosened when the field wiring was disconnected ...

once you've confirmed that your outputs are all capable of turning ON – now go back to the output table and manually turn all of the bits to ZEROs ... all of the LEDs on the front of the module should turn OFF ...

this next part can be tricky ... since you're dealing with a "transistor" type output module, there can be a certain amount of "leakage current" through the output – even though the output is technically OFF ... in many cases, this leakage current is enough to fool the meter – and make it look like the output is "stuck ON" even though the output is OFF ... the best way is to check the outputs for OFF by using something like a 24VDC INCANDESCENT lamp bulb – or a relay coil suitable for 24VDC ...

going further, in many cases, using something like a relay coil or an INCANDESCENT lamp bulb is much better than using a meter in the first place – whether you're checking the output for OFF – or for ON ... the idea is to provide a "realistic LOAD" to the output to counteract the confusing effects of the "leakage current" ...

secret handshake: many transistor type (and TRIAC type) outputs are NOT "contacts" that OPEN and CLOSE like a switch ... instead they are "resistors" (as in tran-SISTORS) that change from a low resistance when they're ON – to a high resistance when they're OFF ... since a voltmeter is an EXTREMELY high resistance, it doesn't present enough "load" to the circuit to provide a realistic test ... so ... use something like a relay coil as your test device to get the most reliable results ...
 
Last edited:
I think he means any rungs in your program which have outputs in this module.

And when he says 'manually change the output bit' you may have to force them. I'm not sure.
 
Usually LAD 2 is the file where your program control logic exists. Change the logic so it is not turning any outputs on or off for the card you question. Then go to the data table for Outputs and change the 0 to 1 for all eight addresses. As each bit state is changed from 1 to 0 the corresponding LED should light on the card. The follow the rest of Ron's instructions for measuring voltage on each terminal.
 
I was able to change all 0's to 1's, however, no indicator lights turn-on, on the output module. I'm thinking I may have missed a step while configuring the output module. It seems pretty straight forward though. I powered off PLC, installed module, went to IO config, selected my module for slot 10, it placed it in slot 10 where is displays my I/O rack. I'm pretty sure that's all I did to install the other modules.
 
Post your .RSS file and some one will take a look at it.

For the above method to work you must not have any logic controlling the
outputs.
 
I was able to change all 0's to 1's, however, no indicator lights turn-on, on the output module.
Click to expand...

are you sure that you were "ONLINE" (communicating with the processor - ladder icon turning) and that the processor was in the RUN mode at that point? ...

as Mickey said, post your RSS file ...
 
I have to wait until production will let me have the control back, to copy the RSS. After deleting all the outputs to the output module, and going to the output table, I was able to change all 0's to 1's. The control is in "run" mode, still no indicator lights.
 
I was able to change all 0's to 1's. The control is in "run" mode, still no indicator lights.
Click to expand...

as long as we're fully understanding each other, the conditions you've given mean that you have either a bad slot in the chassis - or (much more likely) a bad output module ...

take a close look at the electronics on the module's circuit board ... anything look "scorched" or broken? ... how about the pins at the back of the module? ... any bent or broken? ...

sorry - but chances are that your "used" module is just defective ...
 
Everything looks clean. There are still two things I'm not sure of: 1.) When I assigned the module to slot 10, that's all I had to do, right? No other steps needed to enable the board? And, 2.) I ran +24VDC and 0V from existing power supply, through a fuse, and connected them to the very top and bottom terminals (terminal screws are black)of module. It seems pretty straight-forward, right? Thanks much for your replies.
 

Similar Topics

A
1746-HSCE swap
I had a 1746-HSCE go suspected bad. have to swap the card in the morning. Other than dip switch settings is there any configuration to do?
Replies
1
Views
1,023
Ken Roach
Ken Roach
R
Fault on 1746 L551C
Happy Friday everyone! I recently installed a new module, 1746 NIO4I, into the last slot on this chassis. Got the normal IO mismatch fault, added...
Replies
5
Views
1,568
James Mcquade
J
C
1746-N3 Connector
Does anyone know where to get either new or aftermarket 1746-N3 connectors and cables for SLC 32 point discrete in cards? I have a used MCC that...
Replies
1
Views
1,243
Robb B
R
J
1746-OW16 connection issue using 1747-AENTR
I am looking to replace a SLC5/05 processor with an AENTR adapter. Configured the rack in a compactlogix. The connection to all of the cards in...
Replies
5
Views
2,311
JBooth
J
M
Wiring Banner Q5X into a 1746-NIO4V
Heya guys, I'm looking to connect a Banner Q5XKILAF3000-Q8 (4-20mA) signal into my plc which have a analog input card 1746-NIO4V and was...
Replies
0
Views
1,082
Martindag
M
Back
Top Bottom