Siemens SIMATIC Manual page 422

Analog modules
6.11 Analog input module SM 331, AI 6 x TC isolated (6ES7331-7PE10-0AB0)
Technical specifications
Wiring of the signal sensors
1. The integration time of the module at 400 Hz suppression is displayed in HW Config as 2.5 ms. To achieve the required
resolution of 15 bits (plus sign), an integration time of 10 ms is needed.
2. If wire-break monitoring is active, the module cycle is performed within the basic conversion time
+ 65 ms. and the reaction time to a change in the step input is no longer than twice the module-cycle time. If wire-break
monitoring is inactive, in the best-case scenario the module-cycle time is exactly the same as the integration time.
However, this time interval cannot be guaranteed due to the time needed to process the input channels. If wire-break
monitoring is inactive, the reaction time to a change in the step input is no longer than four times the integration time.
3. Common mode interference suppression and crosstalk between inputs are executed at > 130 dB, if 10 Hz, 50 Hz, or 60
Hz has been selected as the interference frequency. If 400 Hz has been selected as the interference frequency, com-
mon mode interference suppression and crosstalk between inputs are implemented at > 110 dB
4. The operational limit comprises only the basic error of the analog input at Ta = 25 °C and the total temperature error.
The total error must include the compensation error of the cold reference junction. Internal compensation of the refer-
ence junction = max. 1.5 °C External compensation of the reference junction = accuracy of the external thermoresistor
used ± 0.1 °C. External compensation of the reference junction, which maintains the reference junction at 0 °C or 50 °C
= accuracy of temperature control for the reference junction.
5. An integration time of 100 ms is recommended for thermocouple measurements. Integration times set lower than this
will result in a higher repeat-accuracy error for the temperature measurements.
6. With thermocouple type B, a missing compensation of the reference junction temperature has no significant effect ow-
ing to its slight increase from approx. 0 °C to 40 °C. With missing compensation and set measuring type "Compensa-
tion to 0 °C", the deviation with thermocouple type B at measuring temperatures between:
– 700 °C and 1820 °C is < 0.5 °C
– 500 °C and 700 °C is < 0.7 °C.
If the reference junction temperature is approximately that of the module temperature, "internal compensation" should
be set. As a result, the error for the temperature range from 500 °C to 1820 °C is reduced to < 0.5 °C.
422
using a 40-pin front connector
S7-300 Module data
Manual, 06/2017, A5E00105505-AJ