Measurement Computing WEB-TEMP - Manual (Page 30)

WEB-TEMP User's Guide Specifications
30
Channel configurations
Table 2. Channel configuration specifications
Sensor Category Condition Max number of
sensors (all channels
configured alike)
Disabled All temperature input channels are disconnected from screw
terminals and internally connected to AGND. See Note 3
Thermocouple (Note 1) 8 differential channels
Semiconductor sensor
(Note 1) 8 differential channels
RTD and Thermistor
(Note 1)
2-wire input configuration with a single sensor per channel pair 4 differential channels
2-wire input configuration with two sensors per channel pair 8 differential channels
3-wire configuration with a single sensor per channel pair 4 differential channels
4-wire input configuration with a single sensor per channel pair 4 differential channels
4-wire input configuration with two sensors per channel pair 8 differential channels
Note 1: Internally, the WEB-TEMP has four, dual-channel, fully differential A/Ds providing a total of eight
differential channels. The analog input channels are therefore configured in four channel pairs with
CH0/CH1 sensor inputs, CH2/CH3 sensor inputs, CH4/CH5 sensor inputs, and CH6/CH7 sensor
inputs paired together. This "channel-pairing" requires the analog input channel pairs be configured to
monitor the same category of temperature sensor. Mixing different sensor types of the same category is
permissible, such as a type J thermocouple on channel 0 and a type T thermocouple on channel 1.
Note 2: Channel configuration information is stored on a EEPROM external to the isolated microcontroller by
the firmware whenever any item is modified. Modification is performed by commands issued over
Ethernet from an external application, and the configuration is made non-volatile through the use of the
EEPROM.
Note 3: The factory default configuration is Disabled. The Disabled mode disconnects the analog inputs from
the terminal blocks and internally grounds (AGND) all of the A/D inputs. This mode also disables each
of the current excitation sources.
Compatible sensors
Table 3. Compatible sensor type specifications
Parameter Specification
Thermocouple J: –210 °C to 1200 °C
K: –270 °C to 1372 °C
R: –50 °C to 1768 °C
S: –50 °C to 1768 °C
T: –270 °C to 400 °C
N: –270 °C to 1300 °C
E: –270 °C to 1000 °C
B: 0 °C to 1820 °C
RTD 100 Ω PT (DIN 43760: 0.00385 ohms/ohm/°C)
100 Ω PT (SAMA: 0.003911 ohms/ohm/°C)
100 Ω PT (ITS-90/IEC751:0.0038505 ohms/ohm/°C)
Thermistor Standard 2,252 Ω through 30,000 Ω
Semiconductor / IC LM35, TMP35 or equivalent