Home > Temperature Controllers > Model 24C > Specifications
User Interface
Display Type:240x64 graphics TFT LCD with LED back-light.
1x font is 4mm, 2x is 8mm.
Number of Inputs Displayed: One to Four.
Keypad: Sealed Silicon Rubber.
Temperature Display: Six significant digits, auto-ranged.
Display Update Rate: 0.5 Seconds.
Display Units: K, C, F or native sensor units.
Display Resolution: User selectable to seven significant digits.
Input Channels
There are four input channels, each of which may be independently configured for any of the supported sensor type.
Sensor Connection: 4-wire differential. DIN-6 Connector.
Sensor Types: See Supported Sensor Section.
Thermocouple: External option. Up to four supported.
Sensor Selection: Front Panel or remote interface.
Input Configurations: See input specifications table.
Bridge Modes: Constant-Current or Constant-Voltage.
Bridge type: Ratiometric resistance bridge.
AC Excitation Frequency: 7.5Hz bipolar square wave.
Voltage Excitations: 10mV to 100uV.
Minimum
excitation current is 50nA.
DC Offset: <30nA.
Sample Rate: 15Hz per channel, all sensor types.
Digital Resolution: 24 bits.
Measurement Accuracy: See input specifications table.
Measurement Drift: 15ppm/°C.
Isolation: Input channel circuits are electrically isolated from all other internal circuitry but not from each other.
Measurement Filter: 0.5, 1, 2, 4, 8, 16, 32 and 64 Seconds.
Calibration Curves: Built-in curves for industry standard sensors plus eight user curves with up to 200 entries each. Interpolation is performed using a Cubic Spline.
CalGen™: Calibration curve generator fits any Diode or resistor sensor curve at 1, 2 or 3 user specified temperature points.
Status Outputs
Audible and Visual Alarms: Independent audible remote and visual alarms.
Relays: Two dry-contact relays. N.O. contacts available. Ratings are 125VAC @ 10A. Maximum switching power: 150W.
Status reported via Remote Interface: Sensor fault, Heater over temperature fault.
Control Outputs
Number of Independent Control Loops: Four.
Control Input: Any sensor input.
Loop Update Rate: 15Hz per loop.
Isolation: Control loop circuitry is electrically isolated from all other internal circuitry.
Control Type: PID table, Enhanced PID, Ramp or Manual.
Autotune: Minimum bandwidth PID loop design.
PID Tables: Six user PID tables available for storage of setpoint and heater range vs. PID and heater range. 16 entries/table.
Set-point Accuracy: Six+ significant digits.
Fault Monitors: Control loops are disconnected upon detection of a control sensor fault or excessive internal temperature.
Over Temperature Disconnect: Heater may be relay disconnected from user equipment when a specified temperature is exceeded on any selected input.
Loop #1 Primary Heater Output
Type: 50-Watt short circuit protected linear current source. Maximum compliance is selectable at 25V or 50V.
Ranges: Three output ranges of 1.0A, 333mA and 100mA full scale, which correspond to 50W, 5.0W and 0.5W.
Minimum Load: 10Ω in 25W setting, 40Ω in 50W setting.
Resolution: 1.0ppm of full-scale power (20 bits).
Readbacks: Heater output power, Heatsink temperature.
Loop #2 Heater Output
Type: 25-Watt, short circuit protected linear current source. Maximum output is 0.45A at 25V.
Ranges: Two output ranges of 25W and 2.5W into a 50Ω load.
Load Resistance: 50Ω for maximum output.
Minimum Load: 10Ω.
Resolution: 1.0ppm of full-scale power (20 bits).
Readbacks: Heater output power, Heatsink temperature.
Loop #3 and #4 Control Output
Loops #3 and #4 are analog voltage outputs that are intended to drive an external booster supply.
Output: User selectable at 10 or 5-Volt full scale..
Resolution: 1.0ppm of full-scale power (20 bits).
Connection: Detachable terminal block.
Remote Interfaces
Ethernet: Ethernet Local Area Network. Electrically isolated. TCP/IP and UDP servers provide remote control by using an ASCII command language. HTTP provides built-in web server. SMTP sends e-mail based on alarm conditions.
RS-232: Serial port is an RS-232 standard null modem. Data rates are 9600, 19,200, 38,400 and 57,200 Baud.
Optional IEEE-488 (GPIB): Full IEEE-488.2 compliant.
Remote Programming Language: IEEE-488.2 SCPI compliant.
LabVIEW™ drivers available for all interfaces.
Data Logging
Data logging is performed to an internal, 1,000 entry circular buffer and is time-stamped with a real-time clock. Buffer memory is non-volatile and will retain valid data without AC power.
User Setups
Four User Setups are available that save and restore the complete configuration of the instrument.
General
Ambient Temperature: 25°C ± 5°C for specified accuracy.
Mechanical: 8.5”W x 3.5”H x 12”D. One half-width 2U rack. Instrument bail standard, rack mount kit optional.
Weight: 9 Lbs.
Power Requirement: 100, 120, 220 or 240VAC +5% -10%. 50 or 60Hz, 150VA.
Conformity: European CE certified. RoHS, Lead Free.
Calibration: NIST traceable.
A unique feature of the Model 24C is the use of a ratiometric AC resistance bridge to measure all types of sensors.
The AC excitation used with all resistor sensors (including Platinum RTDs) is a 7.5Hz bipolar square wave. This effectively eliminates DC offset errors including the thermal EMF induced offsets that often occur in cryogenic systems.
Positive Temperature Coefficient (PTC) resistor sensors including Platinum and Rhodium-Iron RTDs use the resistance bridge in it's constant-current, AC operating mode. Platinum RTD sensors use a built-in DIN standard calibration curve that has been extended to 14K for cryogenic use.
The Model 24C's resistance bridge is used in a constant-voltage AC mode to provide robust support for the Negative Temperature Coefficient (NTC) sensors commonly used by cryogenic applications. They include Ruthenium-oxide, Carbon-Glass, Cernox™, Carbon Ceramic, Germanium and several others. Since these sensors have a negative temperature coefficient, the use of a constant-voltage measurement method will reduce, rather than increase, power dissipation in the sensor as temperature decreases. By maintaining the lowest possible power level, sensor self-heating is minimized and useful temperature range is greatly increased.
An additional advantage to constant-voltage excitation is that NTC resistors lose sensitivity in the upper part of their range. By auto-ranging excitation current to maintain a constant voltage, sensitivity and noise immunity in that range is also improved.
The excitation source in the Model 24C is continuously variable so there are no steps in sensor self-heating.
Diode sensors are supported over their full temperature range by using the bridge in a DC, constant-current mode. This mode provides the required 10µA DC sensor excitation and 0 to 2.25 volt input range
Model 24C Supported Sensors |
||
---|---|---|
Temperature Range |
Example Sensors |
|
Diode | 1.4 - 500K | Cryo-con S950 / S900 SI-440, 430, 410 Lakeshore DT-670, 470 |
Platinum RTD | 14 - 1200K | Cryo-con CP-100 Cryo-con GP-100 Cryo-con XP-100 Cryo-con XP-1K |
Rhodium-Iron | 1.4 - 800K | Oxford PHZ 0002 |
CLTS |
4K to 300K |
|
Germanium | 200mK - 100K | Lakeshore GR-200A |
Carbon Glass™ | 1.4 - 325K | Lakeshore CGR-1-500 |
Cernox™ | 200mK- 325K | Lakeshore, all types |
Carbon-Ceramic | 200mK - 300K | TMi-A1 |
Ruthenium-Oxide | 200mK - 200K | SI RO-600 |
1.4 to 1500K |
All thermocouple types. |
Diode sensors |
PTC resistor sensors |
NTC resistor sensors Constant-Voltage mode |
NTC Resistor Sensors Constant-Current mode |
Thermocouple |
|
---|---|---|---|---|---|
Excitation Mode | DC, Constant-Current |
AC, Constant-Current |
AC, Constant-Voltage |
Constant-Current DC Resistance Bridge |
DC voltage |
Input Range | 2.25V |
750Ω,7.5KΩ and 75KΩ Full-Scale. CLTS 300Ω |
Minimum: 0.5Ω Maximum: 2.0MΩ |
100K - 225KΩ |
±70mV |
Accuracy: % of Rdg + % of Range |
0.005% + 0.0003% |
0.01% + 0.0005% |
14Ω to 30KΩ: 0.05% + 0.05% 0.5Ω to 2MΩ: 0.15% + 0.15% |
0.005% ± 25Ω |
0.05 |
Resolution: % of Range |
0.00004% |
0.0003% |
0.0003% |
0.00004% |
0.0003% |
Excitation Current | 10µA DC |
1.0mA, 100µA, 10µA |
100mV, 10mV, 1.0mV 2.5mA to 50nA, continuously variable |
10µA DC |
N/A |
CalGen™ and Cryo-Con™ are registered
trademarks of Cryogenic Control Systems, Inc. All other product and company names are trademarks or trade names of their respective companies. |
Tel: (858) 756 3900 Fax: (858) 759 3515
Specifications subject to change without notice. ©Cryogenic Control Systems, Inc. 1998 - 2021 |