Measurement DBK90 User Manual
DBK90 56-Channel Thermocouple Module
For use with DaqBook/2000 Series Devices, WBK40, & WBK41
Overview …… 2
Hardware Setup …… 3
Connecting DBK90 Modules to Thermocouples …… 3
Open Thermocouple Detection …… 4
Module Configuration …… 4
Connecting DBK90 Modules to other Devices ……5
Mounting…
DBK90 Modules to Each Other…… 5
One or two DBK90 Modules to a Primary Data Acquisition Device…...6
One, two, or three DBK90 Modules to a DBK60 ……7
DBK90 to a Rack ……8
Vehicle Testing and Noise Reduction……9
Power Connections and Analog Common …… 9
Shielding ……10
TC Common Mode …… 10
Software Setup …… 11
Using a Temperature Calibrator …… 12
DBK90 – Specifications …… 13
Reference Notes:
o Chapter 2 includes pinouts for P1, P2, P3, and P4. Refer to pinouts applicable to your system,
DBK Option Cards and Module 907492 DBK90 pg. 1
as needed.
o In regard to calculating system power requirements, refer to DBK Basics located near
the front of this manual.
Overview
The DBK90 is used in temperature measurement applications and provides connections for 56
thermocouples through convenient mini-TC connectors.
The DBK90 features on-board cold junction compensation (CJC) for direct measurement of type
J, K, T, E, N28, N14, S, R, and B thermocouples. The following table provides the temperature
range for each of these thermocouple types.
Thermocouple Temperature Ranges
T/C Type J K T E N28 N14 S R B
Temperature
Range °C
Temperature
Range °F
-200 to
760
-328 to
1400
-200 to
1200
-328 to
2192
-200 to
400
-328 to
752
-270 to
650
-454 to
1202
-270 to
400
-454 to
752
0 to
1300
32 to
2372
-50 to
1768
-58 to
3214
-50 to
1768
-58 to
3214
Note: There are four CJCs on the DBK90, one per row of thermocouple connectors.
50 to
1780
122 to
3236
Up to sixteen DBK90 modules can be attached to a single DaqBook/2000 Series device, WBK40, or
WBK41. Using Sixteen DBK90 modules provides up to 896 temperature channels.
DBK90 Block Diagram
In comparison to typical DBK options, the DBK90 demands significant power from the
system’s ±15 V power supplies. It is important that you calculate your system’s power
demand, as you may need to add auxiliary power supplies. For additional information
refer to Power Requirements in the DBK Basics section.
pg. 2, DBK90 907492 DBK Option Cards and Modules
Hardware Setup
Connecting DBK90 Modules to Thermocouples
The DBK90 accepts up to 56 mini-TC plugs in its channels 0 through 55. All channels have the same level
of functionality.
Thermocouple wire is standardized, color-coded, and polarized, as noted in the following table.
Thermocouple Standards
T/C
Type
J White Red
K Yellow Red
T Blue Red
E Violet Red
N28 Orange Red
N14 Orange Red
S Black Red
R Black Red
B Gray Red
Mini-TC plugs are type-specific, and for best measurement operation the plug TC type should match the
wire TC type. If necessary, copper/copper (Type U) plugs may be used, but measurement stability will be
slightly degraded. Mini-TC plugs are polarized as well, and it is critical for proper measurement operation
that this polarity be followed when connecting the thermocouple wire. Once wired, the TC plugs will only
mate into the DBK90’s connectors in one orientation, ensuring a correct connection.
(+) Lead to
Channel High
(-) Lead to
Channel Low
Red (-) connects
to Channel Low
The (+) color,
see table,
connects to
Channel High
It should be noted that thermocouples output very small voltages and that long thermocouple leads can
pickup a large amount of noise. If desired, noise reduction can be achieved through the use of shielded
thermocouples and/or averaging.
You can minimize the effect of noise by (1) using shielded thermocouples,
(2) averaging readings, or (3) employing both of these practices.
Each DBK90 includes a jack labeled “ACOM.” The jack is typically used for connecting the shield of a
shielded thermocouple to the DBK90’s analog common. When this connection is made the shield at the
other end of the thermocouple is left unconnected.
If a thermocouple shield is connected to the DBK90 module, leave the shield
unconnected at the other end of the thermocouple. Connecting the shield to common
at both ends will result in a ground loop.
The jack accepts a removable 2mm banana plug for ease of making and breaking the analog common
connection. The 2mm banana plug that is shipped with the product is part number 5936-0 from Pomona®
Electronics.
The ACOM connector is a 2mm banana jack. To ensure a good connection that will not
damage the jack, use a Pomona® Electronics 2mm banana plug (p/n 5936-0). The use of a
different plug (including a 0.08 inch tip type) may damage the ACOM jack.
Reference Note:
In regard to automotive applications, refer to the upcoming section entitled, Vehicle Testing.
The section begins on page 9.
DBK Option Cards and Module 907492 DBK90 pg. 3
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.
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 microswitches to set the desired address. The following figure shows DIP switch settings for the 16 possible
addresses.
CAUTION
DBK90 Channel Address Settings
Each module in the system must have a unique address.
pg. 4, DBK90 907492 DBK Option Cards and Modules
Connecting DBK90 Modules to other Devices
Mounting DBK90 Modules to Each Other – Using Kit # 1109-0800
Each 1109-0800 mounting kit includes two splice bars and eight screws. The kit is only intended for
mounting one DBK90 module to another. However, other kits are available for mounting DBK90s to
primary acquisition devices, for example, to a DaqBook/2000 Series device. Those kits are discussed
shortly.
Two DBK90 Modules, Combined via Kit # 1109-0800
Follow these steps if you desire to mount DBK90 modules to each other using 8-hole splice bars.
1. Push the two DBK90 modules together such that their P1 connectors properly mate. Note that
each DBK90 has a female P1 DB37 connector on one side and a male P1 DB37 connector on
the other.
2. Align four holes of an 8-hole splice bar as indicated in the preceding figure. Note that the two
holes for one DBK90 will be vertical, while the two holes for the other DBK90 will be
diagonal (see figure).
3. Secure the splice bar to the DBK90 modules using the provided screws.
The screws are 8-32 x 1/4 Phillips Pan Head Screws.
4. Use the second splice bar and set of 4 screws, to secure the other side of the assembly.
Note: Additional splice bar kits can be used to add more DBK90 modules to the assembly.
5. Connect one end of a DB37 cable to the DBK90 male P1 connector (see figure).
6. Connect the other end of the DB-37 cable to the male P1 connector located on the primary data
acquisition device.
This completes the procedure.
Note 1:
A female-to-female 37 pin connector can be used to connect a DBK90 to the host data
acquisition device. The use of a CA-143-x shielded cable is recommended for scenarios in
which signal noise is a problem. Page 14 of this section includes a list of cables compatible
with DBK90 use.
DBK Option Cards and Module 907492 DBK90 pg. 5
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