Chapter 5 Specifications; Analog Input; Channel Configurations - Measurement Computing WLS-TC User Manual

Specifications
All specifications are subject to change without notice.
Typical for 25°C unless otherwise specified.
Specifications in italic text are guaranteed by design.

Analog input

Parameter
A/D converters
Number of channels
Input isolation
Channel configuration
Differential input voltage
range
Absolute maximum input
voltage
Input impedance
Input leakage current
Normal mode rejection ratio
Common mode rejection ratio
Resolution
No missing codes
Input coupling
Warm-up time
Open thermocouple detect
CJC sensor accuracy

Channel configurations

Sensor Category
Thermocouple
Channel configuration information is stored in the EEPROM of the isolated microcontroller by the
Note 1:
firmware whenever any item is modified. Modification is performed by commands issued over USB or
wireless from an external application, and the configuration is made non-volatile through the use of the
EEPROM.
The factory default configuration is Type J.
Note 2:
Table 1. Generic analog input specifications
Condition
Thermocouple
±C0x through ±C7x relative to GND
(pins 9, 19, 28, 38)
Open thermocouple detect enabled
f = 60 Hz
IN
f = 50 Hz/60 Hz
IN
15 °C to 35 °C
0 °C to 70 °C
Table 2. Channel configuration specifications
Condition
J, K, S, R, B, E, T, or N
18
Specification
Four dual 24-bit, Sigma-Delta type
8 differential
500 VDC minimum between field wiring and
USB interface
Thermocouple sensor type
±0.080 V
±25 V power on, ±40 V power off
5 GΩ, min
105 nA max
90 dB min
100 dB min
24 bits
24 bits
DC
30 minutes min
Automatically enabled when the channel pair is
configured for thermocouple sensors.
The maximum open detection time is
3 seconds.
±0.25 °C typ
±0.5 °C max
–1.0 to +0.5 °C max
Specification
8 differential channels
Chapter 5