3595-1C1 20 Channel Analogue Reed Relay IMP Replacement of 3595-1C IMP

3595-1C1 - 20 Channel Analogue Reed Relay IMP Replacement of 3595-1C IMP

The 35951C1 is a replacement for the original 35951C unit, which is proving compatible with the original for applications encountered so far. It has similar measurement ranges and accuracies to the original product and offers enhanced measurement resolutions and additional integration times on a per channel basis. It also supports improved drift correct measurement options, without compromising compatibility.

It is compatible with the SNET communications and power supply features of the original product and operates on a network driven from a 35954C for example. It is the same size, has identical fixing positions, and it has interchangeable connector blocks with the original product.



  • Compatible Communications with 3595 series
  • Compatible enclosure and connector blocks
  • Thermocouple, resistance, RTD, voltage and current measurements in rugged enclosure.
  • 20 Channels per Module – precision reed relay isolation. Individually programmable
  • Precision 3 and 4 wire resistance and RTD measurements. (35951Q1)
  • Enhanced 14 to 19/20 bit resolution. 100 to 10 measurements per second
  • Enclosed connector blocks. Dual sensor accurate Cold Junction Compensation
  • Thermocouple health monitoring Temperatures in ‘C or ‘F unit


Number of channels / module: 20/10
Number of poles / channel: 3/6
Connector type input channels: Standard 3595 series Isothermal Enclosure Screw Terminals
Measurement modes: V DC (mV DC, uVDC) Thermocouple CJC temperature
Sensor health: Thermocouple types K,J,T,R,S,E,B,N
Thermocouple compensation: Dual sensors


A-D Converter

Measurement resolutions supported:

  • 19/20 bits at 9 measurements/s
  • 18/19 bits at 20 measurements/s
  • 17 bits at 30 measurements/s
  • 17 bits at 40 measurements/s
  • 15 bits at 80 measurements/s
  • 14 bits at 100 measurements/s
  • Number of bits includes sign counted as 1 bit.

50 Hz Mains frequency interference rejection is provided by 17 and 20bit modes 60 Hz mains interference rejection is provided by 17,19 and 20 bit modes. .

Higher Measurement rates possible by disabling drift correct measurements.


Voltage measuring mode

Input voltage ranges:    +12V >-12V
                                           +2.0V >-2.0V
                                           +200mV >-200mV
                                           +30mV >-30mV

 Automatic range selection is supported.

DC measurement accuracy +/- 0.015% of reading + 0.01% of range + 4uV

Temperature coefficients DC voltage: 25ppm rdg + 0.1uV/ o C
Measurement sensitivity 30mV range 18 bits: <0.25uV 

Additional error at 80 & 100/sec mode 0.03% of range


Thermocouple Measurement Accuracy

Internal Cold junction compensation errors included: (External compensation is also available)

Type                                   Range                               Accuracy

K                                     -100 to 500                             0.5oC

                                        500 to1200                            0.7

                                      1200 to 1600                          3.0 

J                                        -50 to 360                            0.5

                                        360 to 800                            0.7

T                                     -150 to 400                            0.5

R                                          0 to 1600                          2.0

S                                          0 to 1700                           2.2

E                                       -50 to 290                            0.7

                                        290 to 1000                          1.0

B                                     200 to 1600                          4.5

N                                   -200 to 1600                          1.3

                                       -100 to 580                            1.1 5

                                          80 to 1300                          1.3

Displayed sensitivity: <0.1oC

Thermocouple Health Monitoring automatic by resistance measurement sequence.

Current Measurement

Sensitivity ( 100R shunt fitted): <10nA

Accuracy as for voltage ranges + shunt accuracy


Interference Rejection

AC 50/60Hz

Common mode rejection ratio channel group: <0.1uV/V
Single channel common mode rejection ratio: <1uV/V
Series mode rejection ratio 50 or 60 Hz +/- 0.05%: <1uV/V

Note: reed scanners are not suitable for direct connection to power circuits


Overload Protection

Channel overload protection: Passive

                                                       50V continuous



For protection against transients and ground loops.

Isolation test voltage IMP to IMP or to SNET: Tested at 500V


Power Requirement

Connector: Via SNET cable

Voltage: 11 to 48V

Current: <100mA at 12V, <50mA at 24V



SNET Interface: SNET standard compatible

Status LED’s: 4

Function: Power, Communication, ADC fault, Calibration error

Safety: EN61010-1:2010, EN61010-2-30:2010

EMC: EN55011:2009, EN 61326-2-1:2006

Case size: 435*215*34.5mm

Protrusion of cable boots: 45mm

Weight: 3.23kg

Operating Temperature Range:  -20 to 70oC

Relative Humidity(non condensing): 85% at 40oC

Vibration: 1g 10hz to 400Hz in 3 planes

Programming storage: Secure flash memory

Calibration temperature is 21’C