RELAY OVERRIDE on WITH 24VDC Signal High, Low off

[thefunkybuddha]

I am not an expert in ladder logic. I am modifying some code and I need to code an override of a relay that is on O0 of the Jazz outputs. Im landing a 24VDC signal to I0. When the signal is high, I want the Relay to energize. As soon as the signal is low, i want it to de-energize. I have done this in V350 and Samba, but i cant get it to work on the Jazz. The closest I can get is with the reset and set coils. But that latches it. And it is two high signals that will turn it on then off. For some reason, when I replace the same logic with direct coils, i get no response. Please help!

[Flex727]

If this isn't working for you (see attached), then post your code.

[thefunkybuddha]

I downloaded this to the controller....ONLY that just to see if I could get the I/O to work...I get no response when I apply 24VDC to I0 (#15). Just in case I was mistaking about the physical address I applied the signal to all the Inputs...no response. If I jumer 24VDC O0 my relay energizes. Im overlooking something simple...please help. 

[Flex727]

Did you go online with the PLC and see that I 0 and O 0 were energized when the input signal is on?

[thefunkybuddha]

Yes. It is not.

[thefunkybuddha]

If I change the code to this...it works...but it latches. I need momentary, only while the signal is high. 

[kratmel]

Is it n/p input on jazz setup corectly?

Please see in installation manual.

[Flex727]

If you don't see I 0 on when you go online with the PLC then you have a wiring problem with your input. If a Set coil latches, then it means the input flickered on so rapidly that you couldn't see it.

[thefunkybuddha]

I have my power to the controller and the only thing I have actually wired to the controller are the outputs to terminals O-0, O-1, O-2, & O-3. The inputs, until I figure, I have left disconnected.  For the 24VDC signal I am just taking a 20 gauge wire and jumping V+ on the controller to the input I assigned. For example, with the ladder I posted above downloaded to my controller, I will run the wire from the number 1 position of the input terminal block, to the 15 position on the terminal block. 

If I simply change the coil to a set coil, it works to set the relay. But, as I stated above, as when I remove the 24V signal I need the relay to go off. With a set coil it stays energized. If I had my wiring wrong, I would expect it to not work with the set coil. 

[Joe Tauser]

On 12/14/2019 at 12:17 PM, Flex727 said:

If you don't see I 0 on when you go online with the PLC then you have a wiring problem with your input.

Connect a jumper between 0V on the power and the n/p terminal (5).  The n/p terminal sets the voltage reference for the inputs as either sinking (0V = ON) or sourcing (+24V = ON).  

Since you are using a jumper from V+ to the input, this is considered sourcing.

Let us know if this works.

Joe T. 

[thefunkybuddha]

2 hours ago, Joe Tauser said:

Connect a jumper between 0V on the power and the n/p terminal (5).  The n/p terminal sets the voltage reference for the inputs as either sinking (0V = ON) or sourcing (+24V = ON).  

Since you are using a jumper from V+ to the input, this is considered sourcing.

Let us know if this works.

Joe T. 

That did it. Thank you all for your help.  I am a ChemE by education so I have some fundamental gaps I need to fill. 

[Joe Tauser]

Cool.  This is what @kratmel brought up but my experience has been that it is not uncommon for an "electricity is not my first love" type of person gets thrust into PLC Land and schematics can be difficult to interpret by those who don't do it every day.

Sometimes people just need their hand held.  

Joe T.