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Page 4-1
Manual MAIM-16.D1d
Chapter 4: Sensor Interface
Before attempting to program or set up the AIM-16, the overall system of which the AIM-16 is a part
should be defined. The AIM-16 provides the system's interface to the various sensors which supply
data. We suggest that you make a list of sensors by type and location. Where practical, sensors of
one type should be grouped on the AIM-16 card to simplify programming.
Considerations for Thermocouples
It is important that the junction temperature from each card be used in computing the temperature
measured by each thermocouple serviced by that card. In order to minimize errors, the junction
temperature sensor is physically located at a place central to all thermocouple connections. The
junction temperature sensor input is normally jumpered to input channel IN0 of each card. A selection
of Gain=1 is suggested for that channel, as it will produce nominal 24.4 mV/ °C. If the AIM-16 is not
enclosed (e.g., in ACCES' T-Box), then care should be taken that there is not air blowing across the
AIM-16. Moving air can cause a small temperature differential, which results in a "reference junction
error".
A total of eight AIM-16 cards per system may be used with an AD12-8. Thus, up to 120
thermocouple inputs can be accommodated (Eight analog input channels used for reference junction
overhead).
An open thermocouple or "break-detect" signal is available and may be activated by installing two
shorts at each channel where break detect is desired. Break-detect short locations are labelled B1
through B16. For example, install two shorts at the two locations labelled B2 in order to enable the
break-detect feature for channel 2. Now, when an open or missing thermocouple is detected, a
full-scale negative output will be provided on channel 2.
A jumper should be installed in the STD position of the programming point labeled "OFST STD". The
OFFSET feature is used for RTDs, for 4-20mA current measurement, and other current
measurements. This feature will be discussed under appropriate paragraphs on the following pages.