Measurement Computing DBK Part 2 - Manual (Page 178)

pg. 4, DBK90 907492 DBK Option Cards and Modules
Open Thermocouple Detection
The DBK90 is equipped with open thermocouple detection for each channel. This means that a broken
thermocouple wire [or otherwise unconnected input] that is measured will result in an off-scale reading.
This is accomplished by applying a small bias current to each of the channel inputs. Whenever a valid
input is absent, the bias current saturates the input amplifier, resulting in the off-scale reading.
Module Configuration
Up to sixteen DBK90 modules can be attached to a single DaqBook/2000 Series device, WBK40, or
WBK41. Since multiple modules are connected via a parallel interface, each must have a unique channel
address.
CAUTION
Adjustment of the channel address must only be performed when the system
power is OFF. Failure to do so may result in equipment damage.
To assign a channel address to the DBK90 module, first locate the DIP switch on the unit’s underside (the
side opposite of the mini-TC connectors). Four micro-switches [on the DIP switch] are used to set the
module’s channel address in binary. After ensuring that the system power is OFF, adjust the micro-
switches to set the desired address. The following figure shows DIP switch settings for the 16 possible
addresses.
DBK90 Channel Address Settings
Each module in the system must have a unique address.