240 Series Specifications

Input specifications

Standard inputs, (normal mode, reversing1)

 Sensor temperature coefficient Input range Excitation current Display resolution Measurement resolution Electronic accuracy (at 25 °C)Measurement temperature coefficient
Negative  0 V to 7.5 V 10 µA ±0.05%100 µV20 µV±320 µV ±0.01% of rdg(20 µV + 0.0015% of rdg)/°C1
1 mA
Positive0 Ω to 1 kΩ1 mA10 mΩ20 mΩ±0.04 Ω ±0.02% of rdg(1 mΩ + 0.0015% of rdg)/°C1
10 mV
Negative0 Ω to 10 Ω1 mA0.1 mΩ0.1 mΩ + 0.002% of rdg±0.002 Ω ±0.06% of rdg(0.1 mΩ + 0.0015% of rdg)/°C1
0 Ω to 30 Ω300 µA0.1 mΩ0.3 mΩ + 0.002% of rdg±0.002 Ω ±0.06% of rdg(0.1 mΩ + 0.0015% of rdg)/°C1
0 Ω to 100 Ω100 µA1 mΩ1 mΩ + 0.002% of rdg±0.01 Ω ±0.04% of rdg(0.1 mΩ + 0.0015% of rdg)/°C1
0 Ω to 300 Ω30 µA1 mΩ3 mΩ + 0.002% of rdg±0.01 Ω ±0.04% of rdg(0.3 mΩ + 0.0015% of rdg)/°C1
0 Ω to 1 kΩ10 µA10 mΩ10 mΩ + 0.002% of rdg±0.01 Ω ±0.04% of rdg(1 mΩ + 0.0015% of rdg)/°C1
0 Ω to 3 kΩ3 µA10 mΩ30 mΩ + 0.002% of rdg±0.01 Ω ±0.04% of rdg(3 mΩ + 0.0015% of rdg)/°C1
0 Ω to 10 kΩ1 µA100 mΩ100 mΩ + 0.002% of rdg±1.0 Ω ±0.04% of rdg(10 mΩ + 0.0015% of rdg)/°C1
0 Ω to 30 kΩ300 nA100 mΩ300 mΩ + 0.002% of rdg±2.0 Ω ±0.04% of rdg(30 mΩ + 0.0015% of rdg)/°C1
0 Ω to 100 kΩ100 nA1 Ω1 Ω + 0.002% of rdg±10.0 Ω ±0.04% of rdg(100 mΩ + 0.0015% of rdg)/°C1

1 Current reversal used only for resistive ranges
2 Rated temperature coefficient from 15 °C to 35 °C, reduced accuracy from -20 °C to 50 °C

Sensor input configuration

Measurement type 4-lead differential4-lead differential
ExcitationConstant current with current reversal10 µA constant current
Supported sensorsCernox®, platinum, germanium, carbon-glass, rhodium-iron, and Rox™Silicon, GaAlAs
Standard curves suppliedLSCI PT-100,
IEC PT-100,
IEC PT-1000
Input connector5-pin terminal plug5-pin terminal plug


Number of inputs2 (Model 240-2P)
8 (Model 240-8P)
IsolationSensor inputs isolated from other circuits but not each other
Input accuracySensor dependent, refer to Input Specifications table
Measurement resolutionSensor dependent, refer to Input Specifications table

Measurement speed

Normal mode  
Update rate10 rdg/s12.5 rdg/s1,2
Filter100 ms100 ms
High speed mode  
Update rate10 to 1000 rdg/sN/A
Filter1 to 100 ms3N/A

1 Update rate is halved when an input is on the 100 kΩ range with current reversal enabled

2 All inputs enabled

3 Filter settings are tied to the update rate, (filter = 1000/update rate)

Temperature conversionLake Shore calibration curves (linear interpolation)
User curvesEach input has storage for one 200-point curve
Reporting unitsK, °C, °F, V, Ω

Digital I/O — Profibus

Baud rates9.6 k, 19.2 k, 45.45 k, 93.75 k, 187.5 k, 500 k, 1.5 M, 3 M, 6 M, 12 M (auto baud-rate detect)
Identification number0x0F84
Reading data formatSingle precision float (32-bit)
Reading rateMatches update rate of the instrument

Digital I/O — USB

FunctionEmulates a standard RS-232 serial port
Baud rate115,200, 8 data bits, 1 stop bit, no parity, no handshaking
ConnectorUSB micro-B
Reading rateMatches update rate of the instrument


Module configurationModule configured over USB interface
Configuration softwareMeasureLINK™ (free download, supported on Windows 7, 8, and 10)
Firmware updateFirmware updated over USB port


Display128 × 32 pixel OLED
Display unitsK, °C, °F, V, Ω
Display update rate2 rdg/s

Displayed readings22
Readings cyclingFixed (no cycling)3 second hold per pair

Temperature display resolution0.0001° from 0° to 9.9999°,
0.001° from 10° to 99.999°,
0.01° from 100° to 999.99°,
0.1° above 1000°
Sensor units display resolutionSensor dependent, to 5 digits
LED annunciatorsModule status and communication status

Power supply

ConnectionScrew terminal
Voltage requirement24 VDC, ±10%
Current requirement100 mA per connected module
Power distributionMaximum 20 units connected through the DIN rail backplane connector (power supply must be able to source required current)
Internal protectionOver-voltage, under-voltage, and reverse polarity protection


Case materialPolyamide
Mounting35 mm DIN rail (EN 50022)
Water ingressIP20: not protected against harmful ingress of water
Case inflammabilityClass V0 according to UL 94
Sensor connector wire size16 to 28 AWG
Power connector wire size12 to 24 AWG
Size22.5 mm W × 115 mm H × 100 mm L (240-2P)
90 mm W × 115 mm H × 100 mm L (240-8P)
Weight120 g (240-2P)
300 g (240-8P)


ComplianceRoHS; CE
Operating temperature15 °C to 35 °C at rated accuracy, -20 °C to 50 °C at reduced accuracy
Storage temperature-40 °C to 85 °C
Relative humidity0 to 70% at rated accuracy, reduced accuracy up to 95%, non-condensing