Model 218 Specifications

Input specifications

 Sensor temperature coefficient Input range Excitation current Display resolution Measurement resolution Electronic accuracy
Diodenegative0 V to 2.5 V 10 µA ±0.05% 9 100 µV20 µV±200 µV ±0.01% of rdg
negative0 V to 7.5 V10 µA ±0.05%9 100 µV20 µV±350 µV ±0.02% of rdg
PTC RTD positive0 Ω to 250 Ω1 mA ±0.3%10 10 mΩ2 mΩ±0.06 Ω ±0.02% of rdg
positive0 Ω to 500 Ω1 mA ±0.3%10 10 mΩ2 mΩ±0.06 Ω ±0.02% of rdg
positive0 Ω to 5000 Ω1 mA ±0.3%10100 mΩ20 mΩ±0.4 Ω ±0.04% of rdg
NTC RTD negative0 Ω to 7500 Ω10 µA ±0.05%9 100 mΩ50 mΩ±0.8 Ω ±0.04% of rdg

9 Current source error has negligible effect on measurement accuracy
10 Current source error is removed during calibration


Number of inputs8
Input configurationInputs separated into two groups of four (each group must be the same sensor type) — inputs can be configured from the front panel to accept any of the supported input types
Input accuracySensor dependent — refer to Input Specifications table
Measurement resolutionSensor dependent — refer to Input Specifications table
Maximum update rate16 rdg/s total
User curvesRoom for 8 (1 per unit) 200-point CalCurves™ or user curves
SoftCal™Improves accuracy of DT-470 diode to ±0.25 K from 30 K to 375 K; improves accuracy of platinum RTDs to ±0.25 K from 70 K to 325 K; stored as user curves
MathMaximum, minimum, and linear equation (Mx + B) or M(x + B)
Filter Averages 2 to 64 input readings

Sensor input configuration

Measurement type 4-lead differential
Excitation8 constant current sources
Supported sensors Diodes: Silicon, GaAlAs RTDs: 100 Ω Platinum, 1000 Ω Platinum, Germanium, Carbon-Glass, Cernox®, and Rox™
Standard curves DT-470, DT-500D, DT-670, CTI-C, PT-100, and PT-1000
Input connector 25-pin D-sub

Front panel

Display4 line by 20 character backlit LCD display
Number of reading displays 1 to 8
Display units K, ºC, V, and Ω
Reading source Temperature, sensor units, max, min, and linear equation
Display update rateAll displayed inputs twice in 1 s
Temp display resolution0.001º from 0º to 99.999º, 0.01º from 100º to 999.99º, 0.1º above 1000º
Sensor units display resolution Sensor dependent to 5 digits
Display annuciators Remote operation, alarm, data logging, max, min, and linear
KeypadMembrane keypad, 20-key, numeric and specific functions
Front panel features Front panel curve entry and keypad lock-out


IEEE-488.2 interface (218S)

FeaturesSH1, AH1, T5, L4, SR1, RL1, PP0, DC1, DT0, C0, E1
Reading rateTo 16 rdg/s
Software supportLabVIEW™ driver

Serial interface

Electrical format RS-232C
Max baud rate 9600 baud
Connector9-pin D-sub
Reading rate To 16 rdg/s (at 9600 baud)
Printer capability Support for serial printer through serial interface port used with data log parameters


Number16: high and low for each input
Data source Temperature, sensor units, and linear equation
SettingsSource, high setpoint, low setpoint, deadband, latching or non-latching, and audible on/off
ActuatorsDisplay annunciator, beeper, and relays (218S)

Relays (218S)

ContactsNormally open (NO), normally closed (NC), and common (C)
Contact rating 30 VDC at 5 A
OperationEach input may be configured to activate any or all of the eight relays — relays may be activated on high, low, or both alarms for any input, or manually
ConnectorDetachable terminal block

Analog voltage output (218S)

ScaleUser selected
Update rate To 16 rdg/s
Data source Temperature, sensor units, and linear equation
Range±10 V
Resolution1.25 mV
Accuracy±2.5 mV
Min load resistance 1 kΩ (short-circuit protected)

Data logging

Channels1 to 8
OperationData log records can be stored in memory or sent to the printer; stored data may be displayed, printed, or retrieved by computer interface
Data memory Maximum of 1500 single reading records, non-volatile


Ambient temperature15 °C to 35 °C at rated accuracy, 10 ºC to 40 ºC at reduced accuracy
Power requirement100, 120, 220, 240 VAC, (+6%, -10%), 50 or 60 Hz, 18 VA
Size216 mm W × 89 mm H × 318 mm D (8.5 in × 3.5 in × 12.5 in), half rack
Weight3 kg (6.6 lb)
ApprovalCE mark, RoHS


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