Measurement Computing DataShuttle - Manual (Page 66)

6-10 Introduction to Terminal Panels 11-09--01 DataShuttle and DynaRes
Product Specifications
Accuracy
Cold Junction Compensation Error
Type 25°C 15° & 35°C 5° & 45°C
J 0 < 0.25 < 0.6
K 0 < 0.3 < 0.7
E 0 < 0.3 < 0.8
T 0 < 0.4 < 1.2
S 0 < 0.6 < 1.3
R 0 < 0.4 < 1.6
B 0 < 1.0 < 2.0
G 0 < 0.7 < 1.7
C 0 < 0.5 < 1.2
D 0 < 0.6 < 1.8
N 0 < 0.6 < 1.2
Cold junction compensation error is in reference to the temperature of the terminals. For types B and G the
above error applies for measured temperatures above 200ºC only. The cold junction sensor can be
recalibrated at any temperature from 0 to 50ºC to improve the accuracy if it will not be used at 25ºC. The
above table applies only after user calibration of the cold junction.
Cold Junction Temperature Differential
For T21 and T71-TC terminal panels only, the temperature gradient in the air adjacent to the cold junction
plate is attenuated 15 times when AWG #22 gage or smaller thermocouple wire is used. The wires are
bundled together for at least one foot from the cold junction terminals. The error is usually less than 0.1ºC.
For the T31, T35, T71-GP, and T71-RTD terminal panels there is no isothermal plate. The cold junction
compensation error consists of the above table plus the difference between the terminal temperature and the
cold junction sensor. This difference can be several degrees.
Thermocouple Calibration Numbers
The T21 and T71-TC terminal panels are marked near the 50-pin connector with a serial number (SN) and
cold junction compensation number (CCAL). The terminal panel was calibrated with a matching analog
input board at the factory. A change in CCAL by 75 changes temperature measurement 1ºC.
For maximum accuracy, the panel should be used with the analog input board with the corresponding serial
number. For boards with more than one terminal panel attached, the T71-TC with the matching serial
number should be used for Channels 1 through 8.
Digital Input/Output
For the Digital I/O Termination on All Terminal Panel Types
• Each line is individually selected to be an input or output.
• Inputs are TTL and MOS compatible.
• TTL outputs are available at the input terminals when an I/O is set to an output (except on T71):
Low Level: < 0.4 volts at 2 mA (sink)
High Level: > 2.4 volts at 100 µA (source)
• Maximum voltage on any terminal with digital isolation modules installed: up to 300 VAC, depending on
module.
On T31 Terminal Panels Only
• Outputs are high voltage open collector:
Low Level: 50 mA max, < 0.7 volts at 40 mA (sink)
High Level: 30 volts max, <250 µA (source)