Measurement Computing DBK12 - Manual (Page 3)

Card Connection
DBK12 and DBK13 are equipped with screw terminal connectors for easy access to all of the analog
inputs, as well as several analog ground access points. Connections are provided for 16 single-ended or
16 differential inputs. On board, there are factory-installed, 100 K
Ω bias resistors in the L locations for
each channel; these resistors can be removed if desired. (The H locations have no factory-installed
resistors).
1. For single-ended operation, connect the signal’s high end to the high input of the desired channel
and the low end to analog common (J5).
2. For differential operation, connect the signal’s high end to the high input and the low end to the low
input of the desired channel. When using differential input, ground referencing to analog common is
important for accuracy. If necessary, use bias resistors. The two differential measurement
configurations (floating and referenced) are discussed in the Signal Management chapter.
3. After all connections are in place, secure wires to the card at the captive areas at the end of the card.
Nylon tie wraps work well for this purpose.
A path to analog common must exist, either by direct connection or through bias
resistors.
Card Configuration
Factory Default: Input mode – Single-ended
The two variables of card configuration are input mode to the card and channel output to the LogBook or
the Daq device.
1. Using the onboard jumper, JP3, set the signal input mode (see figure).
The jumper and its SE (Single-Ended) and DIFF (Differential) positions
are clearly identified on the board overlay.
• For single-ended inputs, place the jumper in the SE position.
• For differential inputs, place the jumper in the DIFF position.
2. To configure the channel, locate the 16×2-pin header (JP1) located near
the front of the board. JP1’s 16 jumper locations (CH0 through CH15)
match corresponding base channels. Place the jumper on the channel
you wish to use.
Only one channel can be selected on a single card; and all cards in a
daisy-chain must have unique jumper settings. Up to sixteen DBK12s
(or DBK13s) may be connected to your LogBook or to your Daq device.
An optional DBK10 enclosure may be used.
Bias resistors are now factory-installed between the channel lows and analog
common. If you have an early version board, you can still install the bias
resistors. The use of bias resistors is discussed in the Signal Management
chapter.
DBK12, DBK13
Configurations
DBK Option Cards and Modules 879895 DBK12 and DBK13, pg. 3