1756-OB8 vs. 1756-OB32

Hello Group

Hope everyone is well

I've used the 1756-OB32 in the past, but now need to use the 1756-OB8 due to space limitations. I've reviewed the Rockwell literature, and it seems that the OB8 provides the exact same functionality as the OB32, but with fewer points.
However, I'd like to get some other thoughts from fellow PLC users if they can confirm that

Let me know as soon as you can

Many thanks in advance for any help that you can provide

harryggianakis said:

Hello Group

Hope everyone is well

I've used the 1756-OB32 in the past, but now need to use the 1756-OB8 due to space limitations. I've reviewed the Rockwell literature, and it seems that the OB8 provides the exact same functionality as the OB32, but with fewer points.
However, I'd like to get some other thoughts from fellow PLC users if they can confirm that

Let me know as soon as you can

Many thanks in advance for any help that you can provide

Click to expand...

You will not gain any "space" by substituting an OB8 for an OB32, both modules are the same physical size.....

The functionality of both modules is exactly the same. Physically they are same size as well. Good part about OB8 is that whoever will do the wiring will have plenty space.

We have a policy in company not to use 32 channels card, unless client will want exactly those, due to wiring space. 32 cores of .75 looks ridiculous and if you want to replace one core once it has already been wired it is a nightmare.

We have a policy in company not to use 32 channels card, unless client will want exactly those, due to wiring space. 32 cores of .75 looks ridiculous and if you want to replace one core once it has already been wired it is a nightmare.

Click to expand...

If we use the 32 channel cards, we now buy the premade cables from Rockwell.
Not cheap, but looks a lot better, and no scrabbling for the electricians to pull wires out of the loom to check and trace connections up to the card....

I prefer to use the 16 point input cards. They have decent density and you can get the 18 #18AWG wires inside and close the door.

Same goes for the 1769 cards. Even though the 32 point cards are twice as wide, they don't have twice the room for wire, so its impossible to close to the door on the front of the card unless you use really small wire.

harryggianakis said:

... now need to use the 1756-OB8 due to space limitations.

Click to expand...

What do you mean with "space limitations"?

harryggianakis said:

I've reviewed the Rockwell literature, and it seems that the OB8 provides the exact same functionality as the OB32, but with fewer points.

Click to expand...

You're right. Price is something to be considered:

1756-OB8 --> ~ $500
1756-OB16E --> ~ $600
1756-OB16I --> ~ $800
1756-OB32 --> ~ $750