Measurement Computing DBK44 - Manual (Page 2)

The LogBook or Daq device scans the DBK44’s channels at the same 10 µs/channel rate as other DBKs
(256 scans in 2.56 ms in a full system). Each user-installed 5B module offers 500 V isolation from the
system and between channels. The DBK44 has convenient screw-terminal blocks for signal inputs and
excitation outputs (for use with a strain gage or RTD). Cold junction compensators (CJC) are installed and
ready to use with thermocouple 5B modules. Sockets are provided for AC1362 current-sense resistor
modules.
Hardware Setup
Power Considerations
The DBK44 requires +5 and ±15 VDC from a LogBook, Daq device P1
connector, or auxiliary power supply. In some applications, the DBK44 can draw
enough power from the LogBook’s internal power supply via the P1 connector.
However, the 5B power requirements (+5 VDC only) may be greater than the
LogBook or DaqBook/DaqBoard can provide (see table).
For applications with more than 4 channels, it may be better to use
the DBK42 instead of the DBK44. The DBK42 is a 16-channel
module with a built-in power supply.
External power can be obtained from any regulated 5 V source or from a
TR-4 power supply. External power attaches to the DBK44 via onboard
screw-terminal connections (the Auxiliary Power Input J9 Combicon
terminal at the rear of the board).
The 5B38 series strain-gage modules with excitation output require an external power
source. Auxiliary power is also necessary in systems equipped with more than one DBK44.
Prior to using auxiliary power, you must select AUXL on the Power Source Select Jumper
(J10).
DBK44, pg. 2 877095 DBK Option Cards and Modules
CAUTION
Auxiliary power input must not exceed +5 VDC. DBK44 does not regulate auxiliary
power input.
5B
Model
Current
Required
5B30 30 mA
5B31 30 mA
5B32 30 mA
5B34 30 mA
5B37 30 mA
5B38 200 mA
5B39 *170 mA
5B40 30 mA
5B41 30 mA
5B47 30 mA
* Maximum output load
resistance is 750 Ω