Measurement Computing DBK Part 2 - Manual (Page 106)

Hardware Setup
Differential Mode
The DBK53 and DBK54 are designed for floating-type differential measurements. Neither the high nor the
low of the analog input has an inherent bias current return path to the analog common on the module. An
external common pin jack is provided on the outside panel for this bias-current return path. The following
figure shows a typical differential connection.
DBK53 and DBK54, pg. 2 989594 DBK Option Cards and Modules