2-channel thermocouple input terminal with open-circuit recognition KL3312
Run LED1
Error LED1
Run LED2
Error LED2
Top view 
Contact assembly 
Observe for earthed
differential inputs
max. ± 2 V to ground
extended shock and vibration range

KL3312 | 2-channel thermocouple input terminal with open-circuit recognition

The KL3312 analog input terminal allows thermocouples to be connected directly. The Bus Terminal’s circuitry can operate thermocouple sensors using the 2-wire technique. Linearisation over the full temperature range is realised with the aid of a microprocessor. The temperature range can be selected freely. The error LEDs indicate a broken wire. Compensation for the cold junction is made through an internal temperature measurement at the terminals. The KL3312 can also be used for mV measurement.

Technical data KL3312
Number of inputs 2
Power supply via the K-bus
Technology 2-wire
Thermocouple sensor types types J, K, L, B, E, N, R, S, T, U (default setting type K), mV measurement
Connection method 2-wire
Measuring range in the range defined in each case for the sensor (default setting: type K; -100…+1370 °C);
mV measurement: ±30 mV…±120 mV
Resolution 0.1 °C per digit
Conversion time ~ 250 ms
Wiring fail indication yes
Measuring error < ±0.5 % (relative to full scale value)
Electrical isolation 500 V (K-bus/signal voltage)
Current consumption power contacts – (no power contacts)
Current consumption K-bus typ. 65 mA
Bit width in the process image input: 2 x 16 bit data (2 x 8 bit control/status optional)
Configuration no address setting, configuration via Bus Coupler or controller
Weight approx. 70 g
Operating/storage temperature 0…+55 °C/-25…+85 °C
Relative humidity 95 %, no condensation
Vibration/shock resistance conforms to EN 60068-2-6/EN 60068-2-27
EMC immunity/emission conforms to EN 61000-6-2/EN 61000-6-4
Protect. class/installation pos. IP 20/variable
Approvals CE, UL, Ex
Special terminals
KL3312-0010 type J
KL3312-0011 type J in Siemens S5 format
KL3312-0012 type L
KL3312-0013 type L in Siemens S5 format
KL3312-0014 type B
KL3312-0015 type B in Siemens S5 format
KL3312-0016 type E
KL3312-0017 type E in Siemens S5 format
KL3312-0018 type N
KL3312-0019 type N in Siemens S5 format
KL3312-0020 type R
KL3312-0021 type R in Siemens S5 format
KL3312-0022 type S
KL3312-0023 type S in Siemens S5 format
KL3312-0024 type T
KL3312-0025 type T in Siemens S5 format
KL3312-0026 type U
KL3312-0027 type U in Siemens S5 format
KL3312-0028 0…120 mV measurement
KL3312-0029 type K in Siemens S5 format
KL3312-0040 expanded temperature range for type S and L type S: -50…+1700 °C (as supplied type L: -100…+900 °C)
KL3312-0110 type J, Fahrenheit scaling
KL3312-2000 setting of reference junction temperature via process image, unit 1/256° C in a 16 bit word
KL3312-2100 external reference point temperature specification via process image is possible, the unit is 1/256 °C in 16-bit format, fast conversion time 65 ms