5V Inputs

I am somewhat familiar with 110V Ac inputs, and or 24DC Inputs, but I have to work with 5V TTL Open Collector outputs from a test meter.
I can move a jumper to drive my outputs from the meter using an external source, but the voltage still has to be between 5V and 15V.
I am building a sorting machine, and my meter has a centronix cable output.

I want to use the output signals from my test meter as inputs for my PLC.
How do you work with 5V Inputs from this type of source?
Do I use relays, or specify a brick with a certain type of input?.
Thank-you for any comments or suggestions.

Some PLCs will accept 5 VDC inputs directly. Otherwise, you probably want to use a solid state relay to switch 24 VDC from your 5 VDC signal. Opto 22, Bentec, ASI, and many others have these available.

Mr. Bradley,

If the PLC you are using does not provide the capability of doing 5 VDC (TTL) inputs, then you would have to use relays, acting as a switch between the 5 volt side and the 12 or 24 volt side that the PLC can offer. Depending on how often you are receiving feedback from your meter, will determine if you should use solid state or mechanical. Another approach is running your I/O through a DC to DC converter...this will not be inexpensive. A third option would be to create a little interface board using opto isolators.

How many I/O are you going to require for your entire application?

There are companies such as Zworld and Tern that offer 5 volt I/O. You would have to use their Dynamic C programming software (Zworld) or Paradigm C software (Tern).

With the bricks, you basically have to deal with W.Y.S.I.W.Y.G. They are produced in the thousands, so it is difficult for the manufacturer to provide product to be customized.

We have done 5 volt applications with our controllers.

Hope this helps.

God Bless,

Stephen Luft

How many I/O are you going to require for your entire application?

Click to expand...

I only need 6 inputs max and 5 outputs, so I'm not talking anything larger than a brick.
I'll probably have to do like Tom suggests and use an intermediate relay. like Opto 22, Bentec, ASI, etc.
Thank-you
George Bradley

http://catalog.weidmuller.com/asp/datasheet.asp?PN=8092490000
http://www.weidmuller.com/english/news/northamericanews/Microseries

George,

First a comment on Stephen's comment...

For the reasons indicated in the following paragraphs, I don't see any reason what-so-ever for using mechanical relays for either inputs or outputs. You might recall that I'm a proponent for doing everything reasonable to isolate the PLC from the nastiness in the field (Inputs and Outputs). This is simply because it is STUPID to lose a card or, worse yet, a brick, because a field device took out your Output. The following describes why there is no excuse to subject your PLC to such risk.

I believe you'll want to look at the G4 Family of Opto's. They are the legacy (original) Opto Modules. They are great and cheap! $9.50 each - direct from OPTO-22! (Minimum order is one!)

You'll need to install them in racks. A four module rack is about $14 or $15 bucks. An eight module rack is about $30 or $35 bucks.

Since you're working with 5V, they also have Switch Modules with ON/OFF/AUTO (in 5V Control only).

There are some issues with Sinking & Sourcing, but they can be gotten around. I just designed a small system just like you are talking about except it was 24VDC. I ran into the Sink/Source issue... no big deal... A PIECE OF CAKE!

Shout, if you need any help!

I ordered 2 G4PB4 mounts and (6) G4ODC5 modules yesterday.
I talked with Tom Edwards @ Opto 22 and he was totally great.
I get the feeling that that is a well run outfit.
I am fairly confident that I have the sinking / sourcing down, Not Pointing iN
Thanks I will be sure to post if I have any questions.