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Model 346 specifications

Sensor input configuration

Sensor inputs are electrically isolated from other circuits, but not each other

	Base configuration (10 sensors)		Option cards (maximum of 4 installed)
	Inputs A and B	Inputs C1 – C4, D1 – D4	3401 RTD/diode option card	3402 thermocouple option card
Number of sensors	2	8	4	2
Supported sensors	Resistive temperature devices (RTDs) up to 100 kΩ Diodes up to 2.5 V			Thermocouple
Measurement configuration	Dedicated — one excitation and measurement circuit per input	Rapidly scanned — one excitation and measurement circuit for each group of 4 inputs. Each active sensor is excited and updated in turn.		Two dedicated inputs
Update rate	100 ms	100 ms dwell time per scanned active sensor. Disabled sensor inputs skipped. Update rate will vary from 100 ms for a single active sensor per group to 400 ms when all sensors in a group are active.		100 ms
Measurement modes	4-lead differential (I+, V+, I-, V-) 2-lead differential (I/V+, I/V-) with lead resistance compensation (future feature)			2-lead differential (V+, V-), room temperature compensated
Input connector	Normal density, socketed DE-9 D-subminiature (2 sensors per connector)			Screw terminals in a ceramic isothermal block

Thermometry

	RTD (resistive)	Diode	Thermocouple
Excitation	Constant current with current reversal for EMF removal	Constant current	N/A — thermocouples generate voltage without current excitation
Current ranges	7 ranges between 100 nA and 1 mA	10 µA	N/A — Excitation current is not delivered by the instrument
Supported sensor examples	Cernox®, Rox™, and 100 Ω platinum sensors	DT-670 silicon diodes	Most thermocouple types, such as Type E and Type K
Pre-installed standard curves	Platinum: PT-100 Rox: RX-102A Rox: RX-103A Rox: RX-202A	Diode: DT-670	Type E Type K

User curves: Space for up to 40 additional user curves (200-point maximum)

Math: Maximum and minimum, Setpoint stabilization indicator (future)

Filter: Averages 2 to 64 input readings

Additional features: 4-lead break detection with 2-lead failover mode (future), out-of-curve extrapolation (future), boosted resolution mode (future), and sensor redundancy support (future).

Input specifications

Standard measurement inputs and scanner option (Model 3401)

	Sensor temperature coefficient	Input range	Excitation current	Display resolution	Measurement resolution	Electronic accuracy (at 25 °C)^1,2	Measurement temperature coefficient	Electronic control stability³
Diode	Negative	0 V to 2.5 V	10 µA ±0.05%⁴	10 µV	10 µV	±80 µV ±0.005% of rdg	(10 µV + 0.0015% of rdg)/°C	±20 µV
PTC RTD	Positive	0 Ω to 10 Ω	1 mA⁵	0.1 mΩ	0.2 mΩ	±0.002 Ω ±0.01% of rdg	(0.01 mΩ + 0.001% of rdg)/°C	±0.4 mΩ
		0 Ω to 100 Ω	1 mA⁵	1 mΩ	2 mΩ	±0.004 Ω ±0.01% of rdg	(0.1 mΩ + 0.001% of rdg)/°C	±4 mΩ
		0 Ω to 1 kΩ	1 mA⁵	10 mΩ	20 mΩ	±0.04 Ω ±0.02% of rdg	(1 mΩ + 0.001% of rdg)/°C	±40 mΩ
NTC RTD 10 mV	Negative	0 Ω to 100 Ω	100 µA⁵	1 mΩ	1.5 mΩ	±0.01 Ω ±0.04% of rdg	(0.1 mΩ + 0.001% of rdg)/°C	±3 mΩ
		0 Ω to 300 Ω	30 µA⁵	1 mΩ	4.5 mΩ	±0.01 Ω ±0.04% of rdg	(0.3 mΩ + 0.0015% of rdg)/°C	±9 mΩ
		0 Ω to 1 kΩ	10 µA⁵	10 mΩ	15 mΩ + 0.002% of rdg	±0.1 Ω ±0.04% of rdg	(1 mΩ + 0.001% of rdg)/°C	±30 mΩ ±0.004% of rdg
		0 Ω to 3 kΩ	3 µA⁵	10 mΩ	45 mΩ + 0.002% of rdg	±0.1 Ω ±0.04% of rdg	(3 mΩ + 0.0015% of rdg)/°C	±90 mΩ ±0.004% of rdg
		0 Ω to 10 kΩ	1 µA⁵	100 mΩ	150 mΩ + 0.002% of rdg	±1.0 Ω ±0.04% of rdg	(10 mΩ + 0.001% of rdg)/°C	±300 mΩ ±0.004% of rdg
		0 Ω to 30 kΩ	300 nA⁵	100 mΩ	450 mΩ + 0.002% of rdg	±2.0 Ω ±0.04% of rdg	(30 mΩ + 0.001% of rdg)/°C	±900 mΩ ±0.004% of rdg
		0 Ω to 100 kΩ	100 nA⁵	1 Ω	1.5 Ω + 0.005% of rdg	±10.0 Ω ±0.04% of rdg	(100 mΩ + 0.002% of rdg)/°C	±3 Ω ±0.01% of rdg

¹ With current reversal enabled, for RTD measurements
² All input accuracy specifications have a minimum confidence interval of 95% with a test uncertainty ratio of 4:1
³ Control stability of the electronics only, in ideal thermal system
⁴ Current source error has negligible effect on measurement accuracy
⁵ Current source error is removed during calibration

Output electrical characteristics

	Outputs 1 – 4	Outputs 5 – 8
Number of outputs	4	4
Function	Primary heaters	Auxiliary low-power heaters Analog-out temperature reference
Output type	Variable DC unipolar current source	Variable DC unipolar voltage source
Ranges	Two: 200 mA and 2 A	One: 10 V
Compliance⁶	50 V	100 mA
Maximum power	100 W (into 25 Ω load)	1 W (into 100 Ω load)
Heater load range	10 to 100 Ω	≥100 Ω
Connector	Normal density socketed DA-15, D-subminiature	10-pin 2.5 mm detachable terminal block
Grounding	Output referenced to chassis ground
Safety limits	Curve temperature, power up heater off, short and open circuit protection

⁶ Maximum level possible before the output will no longer be able to supply the requested output and power output will be less than communicated by the instrument

Heater groups

Multiple physical outputs can be logically combined to act like a single virtual output. This allows more than 100 W to be safely supplied to a single location, with the use of two or more 100 W heaters.

Number of groups: 2 (output groups 9 and 10)

Groupable outputs: Outputs 1 to 4

Number of outputs per group: 2, 3, or 4

Analog output temperature reference

Produce a 0 V to 10 V reference based on a defined sensor reading. The temperature value corresponding to 0 V and 10 V can be configured by the user to optimize for resolution or temperature range.

Availability: Outputs 5 to 8

Output range: 0 to 10 VDC

Accuracy: ±2.5 mV

Resolution: 0.3 mV

Data source: Temperature or sensor units

Scaling: Linear, range settable

Output temperature control characteristics

Available control modes

	Description	Availability
Open loop	Fixed heater output; input temperature used only for temperature limit protection	All outputs
Closed-loop PID	Heater output changes dynamically to maintain the temperature of an input using PID control	All outputs
Zones	Closed-loop PID control with predefined settings for different temperature zones	Outputs 1 to 4, output groups 9 to 10
Warm-up	Coordinated control of multiple outputs to bring the whole system to room temperature	Outputs 1 to 4, output groups 9 to 10

Closed-loop update rate: 10/s

Closed-loop setpoint ramping: 0.1 K/min to 100 K/min

Zone control: 10 temperature zones with P, I, D, manual out, range, control input, ramp rate

Interface

USB host (front panel)

Type: USB 3.0, mass storage class (MSC) device

Function: Firmware updates, diagnostic logs

Connector: USB Type-C™

USB device (rear panel)

Type: USB 2.0

Function: Command and control, emulates a standard RS-232 serial port

Baud rate: 921,600

Connector: B-type USB connector

Ethernet

Function: TCP/IP command and control

Communications protocol: IPv4 and IPv6

Connector: RJ-45 Gigabit Ethernet

Optional IEEE-488.2

Capabilities: SH1, AH1, T5, L4, SR1, RL1, PP0, DC1, DT0, C0, E1

Reading rate: To 10 rdg/s on each input

Software support: ColdSync™, MeasureLINK™, LabVIEW™, Python™

Relays

Number: 2

Contacts: Normally open (NO), normally closed (NC), and common (C)

Contact rating: 30 VDC at 2 A

Operation: Activate relays on high, low, or both alarms for any input, or manual mode

Connector: 10-pin 2.5 mm detachable terminal block

Digital inputs

Number of inputs: 2

Isolation: Optical

Maximum low-level input voltage: +1 V

Minimum high-level input voltage: +4 V

Safe input voltage range: -5 V to +35 V

Operation: Reset min/max, All off (pending)

User-exposed +5 V supply range: Typical 5 V ±10% up to 100 mA continuous

AUX 24 VDC input

Function: Provide auxiliary power to possible future option cards that may require it

Isolation: Isolated from all other internal instrument power supplies

Operating range: 24 VDC nominal, 22 VDC minimum, 26 VDC maximum

Maximum allowed current draw: 2.5 A

Protections: Over current, over voltage, under voltage, inverted polarity

Front panel

Display: 5 in capacitive touch, color TFT-LCD WVGA (800 × 480) with LED backlight

Power switch: SPST mains/line power switch

General

Ambient temperature: 15 °C to 35 °C at rated accuracy; 5 °C to 40 °C at reduced accuracy

Power requirement: 100 to 240 VAC (universal input), 50/60 Hz, 520 VA maximum

Size: 435 mm W × 89 mm H × 368 mm D (17 in × 3.5 in × 14.5 in), full rack

Weight: 6.1 kg (13.4 lb)

Approval: CE, CSA, NRTL mark (contact Lake Shore for availability)

Altitude: <2000 m