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)??

Depends on what you are using the inputs for. 12 bit resolution means you will have 4096 counts. Based on a 10 volt input, the resolution would be about 2.4 mV per count. For some applications this is plenty, for some it would be unacceptable. What type analog sensor are you planning on using? The IF4 can do voltage and current, but the 1400 embedded analog is limited to voltage only.

Instead of dividing the 10 volts in 4096 steps divide the measurement range instead. I think this gets a better understanding. If you have a position sensor 0-1000 mm then the resolution is 0.24 mm.

Then decide if this is good enough for your application.

12 bit is sufficient for most applications even for PID control. If you are to do positioning and need good accuracy I would go for SSI sensors instead.