I noticed that SC-2345 carrier has J1-8 for 2nd stage analog input and J9-16 for 1st stage analog input. I am wondering what the 2nd stage and 1st stage are? I have RTD01 and CI20 modules, are they 1st or 2nd stage?
You can use some modules in a "1stage-2stage setup". That means that you're doing two types of signal conditioning on your incoming signal. Check this knowledgebase for more informations.