Measurement DBK81 User Manual

DBK81, DBK82, and DBK83 Thermocouple Cards

Overview …… 1
Hardware Setup …… 2

Software Setup …… 7
Using a Temperature Calibrator …… 8
DBK81, DBK82, DBK83 – Specifications …… 9

Overview

DBK81 – 7 Channel Card
DBK82 – 14 Channel Card

Card Connection …… 2
Open Thermocouple Detection …… 3
Installing the DBK82 in the DBK41 Enclosure ……3
Using the Connection POD, DBK83 Only…… 4
POD-1 Dimensions ….. 5
Card Configuration …… 6
DaqBook/100 Series & /200 Series and DaqBoard [ISA type] Configuration …… 6
DaqBook/2000 Series and DaqBoard/2000 Series Configuration …… 6

Reference Notes:

o Chapter 2 includes pinouts for P1, P2, P3, and P4. Refer to pinouts applicable to

your system, as needed.

o In regard to calculating system power requirements, refer to DBK Basics located

near the front of this manual.

The DBK81, DBK82, and DBK83 are used in temperature measurement applications that make use of
thermocouples. The DBK81 provides connections for 7 thermocouples. Both the DBK82 and the DBK83
provide connections for 14 thermocouples. The two 14 channel cards differ from each other in that the
input connectors of the DBK82 are on the board, but connectors of the DBK83 are located in an external
connection pod.

DBK83 – 14 Channel Card with

External Connection Pod

All three cards feature 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

50 to
1780

122 to
3236

The three DBK cards connect to external thermocouples via channels, as follows:

• DBK81 – up to seven thermocouples can be connected, using channels 1 through 7, inclusive

• DBK82 and DBK83 - up to fourteen thermocouples can be connected, using channels

1 through 7 for the first seven and channels 9 through 15 for the second set of seven.

Note: On the DBK81, there is one CJC. It is measured on channel 0. On the DBK82 and DBK83 there

are two CJCs, measured on channels 0 and 8.

In addition to thermocouple measurements, each input channel can be configured for a fixed voltage gain
of 100. When in this mode, voltage can be measured in the range of ±100 mV, or ±50 mV, depending on
the type of Daq device being used.

Up to sixteen DBK81, DBK82, or DBK83 cards can be attached to a single LogBook or Daq device,
providing up to 224 temperature channels. The cards need not be the same. For example, you could have
ten DBK81 cards, three DBK82 cards, and three DBK83 cards in one system.

DBK Option Cards and Modules 989494 DBK81, DBK82, and DBK83 pg. 1

*The DBK81 block diagram can be applied to the DBK82 and DBK83, as their diagrams only differ to the

one above in regard to the number of input channels provided.

Hardware Setup

Card Connection

Connect the thermocouple wires to the intended input terminals on the card. The DBK81 provides input
connections for channels 1 through 7, while the DBK82 and DBK83 offer input connections for channels
1 through 7 and 9 through 15. All channels have the same level of functionality.

Thermocouple wire is standardized, color-coded, and polarized, as noted in the following table.

DBK81 Block Diagram*

In comparison to other DBK cards, the DBK81, DBK82, and DBK83 demand significant
power from the system’s ±15V power supplies. It is important that you calculate your
system’s power demand, as you may need to add auxiliary power supplies.
Refer to Power Requirements in the DBK Basics section for additional information.

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

(+) Lead to

Channel High

(-) Lead to

Channel Low

Input connections for the three cards are labeled “H” and “L” to denote polarity.

For isothermal performance, an exposed, grounded copper plane surrounds the input
connectors. It is important that non-insulated input wires do not contact the grounded
plane − since such contact can degrade measurement integrity.

pg. 2, DBK81, DBK82, & DBK83 989494 DBK Option Cards and Modules

It should be noted that thermocouples output very small voltages and that long thermocouple leads can
pickup a large amount of noise. However, the DBK81, DBK82, and DBK83 inherently provide a high
level of noise immunity via their 4 Hz signal bandwidth and input filtering. If desired, further 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.

To accommodate shielding, grounded connections, labeled “SHIELD,” are provided. A typical use of the
connection would be the attachment of the shield to a shielded thermocouple.

If a thermocouple shield is connected on the DBK card, leave the shield
unconnected at the other end of the thermocouple.

Open Thermocouple Detection

The DBK81, DBK82, and DBK83 are 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. When in this “off-scale” state, however, the input amplifier draws more current from the power
supply. Specifically, the power draw of a card from ±15 V will increase by 0.75 mA for each open
channel.

If available power is limited, short unused channels by connecting a short length of wire
between the H and L terminals. This will minimize power consumption. Note that it is not
enough to simply avoid scanning unused channels; to minimize power consumption the
channels must be physically shorted in the hardware.

The power requirements, detailed in the product specification, assume worst case
connection conditions.

Installing the DBK82 in the DBK41 Enclosure

Because of its physical size, the DBK82 will not fit into 1-slot enclosures such as the DBK10 or
DaqBook/216. It does fit, however, in the DBK41 enclosure, and in “drawer-type” products, such as the
DaqBook/260.

Installation of the DBK82 is possible in DBK41 connectors CN3, CN5, CN7, and CN9. The connector
labels are visible near the upper edge of the DBK41’s printed circuit board, as indicated in the following
figure.

DBK41’s Printed Circuit Board

DBK82 cards can be connected to CN3, CN5, CN7, and CN9.

DBK Option Cards and Modules 989494 DBK81, DBK82, and DBK83 pg. 3