1734-ib8

[Prayder]

We have a 1734-IB8 card that only has one input landed on it but we keep continually blowing the card up because of that input. Is there something we could do to keep that from happening? This input is only one place in the logic and we are just using a 2-POS switch to allow signal back to the card.

 

[Ken Roach]

we keep continually blowing the card up because of that input.

Add a simple interposing relay that's driven by the selector switch, and use the relay contacts to drive the POINT I/O input. I like the A-B 700H ones, especially the solid-state 700-HLS1Z24 models.

Whatever's going on in your power system that is destroying the input module will then just destroy the relay, which should be cheaper to replace.

 

[Prayder]

So your saying add something like an Ice Cube relay and have that actually provide voltage to the input card?

 

[Ken Roach]

Yes; I like those slim, inexpensive terminal block style relays.

The 1734-IB8 isn't particularly rugged, but it should still tolerate inputs up to about 50V DC before actually being damaged. If you're literally physically damaging the module, there's something that's putting voltage spikes onto that input wire.

I've commissioned hundreds of POINT I/O modules and the only one's I've damaged are ones that had voltages far in excess of their maximum applied (480V onto a 24V module, or 24V onto a thermocouple).

 

[Prayder]

Thank you Mr. Ken. As always a wealth of knowledge!

 

[Mad_Poet]

Silly question (I hope)

Any chance you are feeding the input with a 120 Vac signal?

I knew a vendor once who was trying to replace a system we used to have. It had two motors and a selector switch to decide which motor to run. The idjit wired the selector switch to a 24 Vdc input module . . . but the voltage to the switch was 120 Vac. (I was surprised it didn't smoke the entire module.)

MadPoet.

 

[Prayder]

Silly question (I hope)

Any chance you are feeding the input with a 120 Vac signal?

I knew a vendor once who was trying to replace a system we used to have. It had two motors and a selector switch to decide which motor to run. The idjit wired the selector switch to a 24 Vdc input module . . . but the voltage to the switch was 120 Vac. (I was surprised it didn't smoke the entire module.)

MadPoet.

Actually this system is brand new and we do have 24 vdc at the switch and tested back to the input. It was also 24 vdc.

 

[Mark Snodgrass]

Can you list the modules and power supplies for the Point I/O, left to right. If you are using different voltages, how they are arranged can make a difference.

 

[mbartoli]

Installing an interposing relay should not be a problem. We have used panels that provided relay (or solid-state) isolation for all inputs and outputs to avoid just such a condition. When I worked for an integrator, we had customers that required it.

 

[ronv5300]

Gents, totally new to AB here. How can I test the input on the 1734-IB8 card, to ensure the card is ok? Currently connected to an Actuator driving HVAC damper. Current status is OK indication is green, and the other inputs are ok.

 

[AlfredoQuintero]

Gents, totally new to AB here. How can I test the input on the 1734-IB8 card, to ensure the card is ok? Currently connected to an Actuator driving HVAC damper. Current status is OK indication is green, and the other inputs are ok.

Maybe you would like to start a new thread for this inquiry. It's kind of the etiquette of this forum when you have a new issue, even if related to the topic, so that it can be discussed separately.