Wiring Point I/O OB4E Output Module

How do you wire a load to the OB4E Point I/O module. Even though each pt. is capable of 1A. with a module total of 3A., this is being supplied by the Point bus. I'm using an AENT module, which according to tech. support can only supply 1A. It looks like you can't wire an external 24VDC source to the module. I'm not sure if you can with the OB2E which has the V terminals. I've never used Point I/O before. Thanks!

Use the point IO power supply http://ab.rockwellautomation.com/IO/1734-POINT-IO-Power-Supplies

Some modules can use external 24 VDC and 120 VAC also.

Also the PS in your comms adaptor should give you 8-10 amps from memory. I like to do outputs as external feed though.

So for 24VDC I would use a 1734-EP24DC? I don't understand why you can supply an external supply to these modules. Then why does the OB2E have V terminals? What are they for? I used the IAB to configure this.

The Plc Kid said:

Also the PS in your comms adaptor should give you 8-10 amps from memory. I like to do outputs as external feed though.

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I'll need to check but tech. Support told me it was 1A.

OK. The point Bus (5V. ) is 1A. The 24VDC can supply 10 A. These are for the AENT comm module. So does that mean if I need 10 A. Output, the 24VDC supply to the AENT will need to supply at least 10A.

POINT I/O can get a little confusing if you just look at the detail diagrams for the I/O modules. Take a bit of a step back and look at the various ways that the POINT I/O Selection Guide 1734-SG001 illustrates power distribution. It does a good job of explaining the different ways the EP24DC, the EPAC, and the FPD modules distribute and separate power.

When you connect 24V DC to the 1734-AENT's terminal block, that power goes both to the internal electronics and the communication POINTBus, as well as to the Field Power bus along the POINT I/O assembly.

There is a DC/DC converter that provides 5V to the POINTBus and the AENT adapter itself. That's the 1 Ampere value that's been discussed.

You can see the Field Power bus on the 1734 bus connector; it's the two larger slider connectors closest to the terminal blocks.

Depending on the type of module, +24VDC and DC Common are brought through the POINT I/O modules to the terminal blocks. Some modules route both +24V and DC Common to the terminals, some route just one, and some route neither. This was the hardest thing for me to wrap my head around; I was looking at the power bus and assuming that the terminal blocks somehow connected directly into it.

In the case of the 1734-OB4E, you get four terminals for the Outputs themselves, and four DC Common terminals you can connect to the common side of each load.

You could connect a hefty 10 A DC power supply to the POINT adapter and run everything along the POINT power bus, or you could use separate power supplies for the network adapter and the bulk power, using a 1734-FPD to isolate the AENT adapter from the power bus.

I'll re-read the manual again. I used the IAB to configure it initially. Do you know about the OB2E and its separate V terminals? Can an external supply be wired here?

The 1734-OB2E has V+ supply terminals for the same reason you have an appendix; it was already there and there wasn't a good reason to remove it.

If you wired a +24 VDC supply to that terminal, it would backfeed the power bus and connect to the same +24VDC terminals at the 1734-AENT. I can't think of a good reason to do that; it's like hooking up a water tower to your garden hose and trying to water your neighbor's lawn.

If you want to power the 1734-AENT and the 1734 I/O from different power supplies, install either a 1734-FPD or 1734-EP24DC.

Which one you use depends on whether you need to extend the POINTBus 5V power to support more modules (EP24DC), or if you just need to put a new, separate source on the POINT power bus (FPD).

The 1734-OB2E has V+ supply terminals for the same reason you have an appendix; it was already there and there wasn't a good reason to remove it.

Good one! I was just trying to determine if there was any advantage to use a OB2E over a OB4E in terms of the power wiring. I guess there isn't. Thanks for your help. I only need 4 DI and 4DO, both 24VDC.