NOTE: The S-TEMP has now been replaced by the TS4085. This information is provided to support S-TEMP units already in the field.

## Description

The Comlab S-TEMP temperature sensor module allows temperature readings from –55°C to +50°C. Designed as an add-on for the DV-208/216 and DV-Mini remote monitoring units, it can however, be used with other equipment by applying the Thevenin equivalent circuit model to determine output values.

The S-TEMP electronics are housed in a small metal enclosure that measures 33mmH x 75mmW x 52mmD (1.3 x 3 x 2 inches), and the module weighs less than 90g (3oz). Typical measurement accuracy is ± 2°C.

Values given in the following instructions apply only to S-TEMP units with serial numbers ST12431-51 and higher. Corresponding data for earlier S-TEMP units are given in the Notes section, at the end of this article.

There are three user connections on the S-TEMP module: +12, OUT, and GND. Normally, the +12 and GND connections can be taken from rear-panel output points where available, or the 12Vdc +/- supply connections for the Davicom unit can be used.

Normal power input to the S-TEMP is +12Vdc, but all units (new and old) can be powered with any value up to a maximum of 30Vdc. In all cases, the input voltage at the +12 terminal must be a MINIMUM of 4 volts HIGHER than the highest expected output of the S-TEMP unit. The normal output voltage range for the new S-TEMP units is 1.69V to 2.5V for the -55°C to +50°C measurement range. Therefore, the input voltage at the +12 terminal MUST be 6.5Vdc or higher, to ensure accurate measurements.

The Thevenin equivalent series resistance for the new S-TEMP units is 7.74Kohms, and the formula to calculate the output for infinite load is:

## DV-Mini Connection Procedure

**1-** Use DavLink to connect with the DV-Mini unit, and select the metering input (Axx) that will be used with the S-TEMP. Configure the Axx input parameters as desired. Refer to the Davlink User Manual for specific details on configuration.

**2-** To ensure correspondence between sensor values and voltage levels at Axx, specific values for the Sensor Coefficients must be entered in fields A, B, C and D, and the proper voltage scale must be selected. Note the minus (-) sign in coefficient C.

DV-Mini Coefficients & Scale: A=0, B=130.22, C=-273.2, D=0, scale set at 2.5V. Note that these coefficients are used for applications that do not require a high level of measurement accuracy. If you want to obtain better accuracy, you need to make all the required connections (steps 3-5) and calculate your own “B” coefficient (steps 6-9).

**3-** Connect the +12 terminal on the S-TEMP to the DV-Mini +12Vdc input voltage source.

**4-** Connect the GND terminal on the S-TEMP to an AGND connection point from the DV-Mini.

**5-** Connect the OUT terminal of the S-TEMP to the DV-Mini Axx input.

**6-** In DavLink, select the metering input (Axx) that is used with the S-TEMP. Configure the Axx input parameters as follows: A=0, B=1 and C=0. Ensure that jumper for Axx is set for 2.5V range. The value displayed in the Global View window for Axx is the actual voltage output (Vo(real)) corresponding to the temperature.

**7-** Using a thermometer, measure and note the S-TEMP temperature (T(real)).

**8-** Use (Vo(real)) and (T(real)) in the following formula to calculate the B’ coefficient.

**9-** Reconfigure the Axx input Sensor Coefficients: A=0, B=B’, C=-273.2, D=0, scale set at 2.5V.

## DV-208/216 Connection Procedure

**1-** Use DavLink to connect with the Davicom unit, and select the metering input (Axx) that will be used with the S-TEMP. Configure the Axx input parameters as desired. Ensure that jumper for Axx is set for 2.5V range. Refer to the DavLink User Manual for specific details on configuration.

**2-** To ensure correspondence between sensor values and voltage levels at Axx, specific values for the Sensor Coefficients must be entered in fields A, B, C and D, and the proper voltage scale must be selected. Note the minus (-) sign in coefficient C.

DV-208/216 Coefficients & Scale: A=0, B=134.22, C=-273.2, D=0, scale set at 2.5V. Note that these coefficients are used for applications that do not require a high level of measurement accuracy. If you want to obtain better accuracy, you need to make all the required connections (steps 3-6) and calculate your own “B” coefficient (steps 7-10).

**3-** Connect the +12 terminal on the S-TEMP to a +12Vdc output from the DV-208/216.

**4-** Connect the GND terminal on the S-TEMP to an AGND connection point from the DV-208/216.

**5-** Connect the OUT terminal of the S-TEMP to the DV-208/216 Axx+ input.

**6-** Connect the DV-208/216 Axx- input to AGND.

**7-** In DavLink, select the metering input (Axx) that is used with the S-TEMP. Configure the Axx input parameters as follows: A=0, B=1 and C=0. Ensure that jumper for Axx is set for 2.5V range. The value displayed in the Global View window for Axx is the actual voltage output (Vo(real)) corresponding to the temperature.

**8-** Using a thermometer, measure and note the S-TEMP temperature (T(real)).

**9-** Use (Vo(real)) and (T(real)) in the following formula to calculate the B’ coefficient.

**10-** Reconfigure the Axx input Sensor Coefficients: A=0, B=B’, C=-273.2, D=0, scale set at 2.5V.

## NOTES

**1-** Refer to the DV-200 technical documentation for rear-panel-connector pinout information.

**2-** On earlier S-TEMP modules, I, O, and G markings correspond respectively to the +12, OUT and GND labels on new units.

**3-** Normal output voltage range for earlier S-TEMP units is 5.69V to 8.00V for the -55°C to +33°C measurement range.

**4-** Input voltage at I terminal of earlier units MUST be 12Vdc, or higher, for accurate temperature measurement.

**5-** Earlier S-TEMP DV-Mini Coefficients & Scale: A=0, B=40.81, C=-273.2, D=0, scale set at 10V.

**6-** Earlier S-TEMP DV-208/216 Coefficients & Scale: A=0, B=39.56, C=-273.2, D=0, scale set at 10V.

**7-** The Thevenin equivalent series resistance for earlier S-TEMP units is 26.1Kohms, and the formula to calculate the output for infinite load is: