Resolution Question

Quick question...I am currently designing a system with a Micrologix 1400 with an additional IF4 (4 analog input) and a OF4 (4 analog output) card. The IF4 has 15 bit resolution, and the OF4 has 12 bit resolution. My question is this. Is it worth it to spend the extra money to do get this set up, or would it be better to save some money and just get the Micrologix 1400 that has analog ins/outs built in (both in and out have 12 bit res)??

I guess it depends on your process/application. If you don't need any great precision or accuracy and the 0-10V is compatible for your devices then the on board can work out cheaper.
The dedicated expansion modules are more flexible (configuration etc) and have a greater resolution, but obviously, as you stated, at a price!

Hope this helps,

Rob

12 bit output resolution is generally sufficient. What output device can resolve equal to or better than one part in 4000? Not many.

12 bit resolution of thermocouple data over an entire span can be loose. K type T/C's have a range of roughly 0 to 2400°F.
2400/4000 = 0.6° minimum change; but given; but like Kidblue says, it depends . . .

Of course, any of these AI's is probably current (0/4-20mA) or voltage, not T/C, so you'd be using a T/C transmitter in the first place, and it could be ranged to 1000 to 2000 to get 0.25° resolution.

I'd be more interested in whether one or the other was differential and isolated, as opposed to single ended with a common ground for all inputs. You're more likely to have trouble with ground loops with single ended inputs.