Spirax Sarco SX90 process controller is a 1/8DIN panel-mounted controller for constant setpoint control in systems with fixed preset setpoints. The controller provides multiple inputs and outputs for PID control of industrial processes and can be used with Spirax Sarco pneumatic and electric control valves, as well as electronic and electrical equipment.

Features

• Universal inputs: RTD, thermocouple, mA, and mV.

• Universal outputs: VMD (valve motor drive), continuous mA and voltage, relays, and logic signals for on/off control.

• Auxiliary power supply: for external transmitters requiring 24VDC.

• Setpoints: locally adjustable, remotely adjustable, or selectable from 4 setpoints.

• Ramping: controls the rate of change between one setpoint and another, with two independent slopes for ramp-up and ramp-down.

• Remote setpoint: for cascade control of two controllers (master/slave) or remote setpoint control.

• Retransmission: for retransmission of the process value or setpoint, or use as a second analog output.

• Event alarms: 4 programmable relay outputs for deviation, band, and process value alarms.

• Quick code: 5-digit quick code for simple controller setup and commissioning.

• Serial communications: up to 64 controllers can be connected to a management system through 5-wire RS485 serial communications.

• Automatic/manual: automatic and manual modes can be selected using the keypad or logic inputs.

• Logic inputs: 3 logic inputs provide multiple selection functions.

• Potentiometer input: for valve position feedback.

• Text messages: configurable scrolling text messages can remind users to monitor process conditions.

• Forced output: the forced output level is determined by instrument parameters and can be activated through a logic input or by writing a parameter.

Certifications

• Complies with 93/68/EEC and EN61010-1:90 requirements for essential protection conditions for electrical equipment.

• EMC emissions: EN 61326-1: 1997 Class B, including amendments A1, A2, and A3.

• EMC immunity: EN61326-1: 1997 industrial locations, including amendments A1, A2, and A3.

Technical Specifications

General Technical Specifications

Item	Details
Mounting	1/8DIN panel mounting
Power supply	85 - 265Vac, maximum power 9W
Electrical connections	Screw terminals
Enclosure rating	IP65 - front panel insertion, NEMA 4X
Operating temperature and humidity	Temperature 0 - 55℃, humidity 5% - 85%
Environment	Not suitable for explosive or corrosive environments
Electromagnetic compatibility (EMC)	EN 61326
Electrical safety BS EN 61010	Installation Category II
Weight	350g
Certification	CE

Process Variable Input

Item	Details
Calibration accuracy	< ± 0.25%( ± 1 least significant digit LSD)
Resolution	<0.5μV(1.6s filter)
Input filter	Off to 59.9s
RTD	Three-wire PT100, DIN43760
Excitation current	0.2mA
Universal linear mA	4 - 20mA, 0 - 20mA, using an external 2.49Ω shunt resistor
Linear input range	-10 - 80mV
Thermocouples	K, J, N, R, S, B, L, T, C, custom
Sampling rate	4Hz(250ms)
Cold junction accuracy	< ± 1°C at an ambient temperature of 25℃
Linear mA accuracy	<0.1% of reading
Input impedance	100MΩ
Number of setpoints	3 setpoints plus remote setpoint
User calibration	Two-point gain and offset

Transmitter Power Supply

Item	Details
Insulation	300Vac double insulation
Output voltage	18V ± 15%
Current	30mA maximum
Load regulation	<1V, 25mA

Control Action

Item	Details
Proportional band	1 - 9999 engineering units, 0.01 - 300, 0.1 - 3000
Integral time	Off - 9999
Derivative time	Off - 9999
Error band	One-shot tuning or natural frequency tuning. The controller automatically selects the best method according to process conditions.
Auto-tuning	Hysteresis 0.01 - 300.0 or 0.1 - 3000 engineering units
On/off control	1 - 9999 engineering units, 0.01 - 300, 0.1 - 3000.
Cutback	Minimizes overshoot in critical processes.
Automatic/manual mode	Selected from the keypad
Relay insulation	300Vac double insulation
Logic inputs (x3)
Contact closure	Open >1200R, closed <300R
Communications insulation	300Vac double insulation
Hardware	EIA 485 5-wire, EIA 422 compatible
Protocol	Modbus RTU Slave

Remote Setpoint Input

Item	Details
Insulation	300Vac double insulation
Calibration accuracy	< ± 0.25%( ± 1 least significant digit LSD)
Sampling rate	4Hz(250ms)
Resolution	>14bits - 0.5mV(0 - 10V input), 2μV(4 - 20mA)
Input impedance	>222KΩ(voltage), >2.49Ω(current)
Linear input range	0 - 10V, 0 - 20mA
Input filter	Off - 59.9s
Zero offset	User-adjustable over the full range
User calibration	Two-point gain and offset

Potentiometer Input

Item	Details
Potentiometer resistance range	100 - 10kΩ
Excitation voltage	0.46 - 0.54V
Resolution	0.006% of range, greater than 14Bits
Sampling rate	1Hz
Shorted potentiometer detection	<25Ω
Open potentiometer detection	>2MΩ
Open wiper detection	>5MΩ
Contact rating	Maximum 2A at 264Vac resistive, 2A current. For AB terminals, maximum 2A.

Outputs

Item	Details
Output 1	SPST normally open contact
Output 2	0 - 20mA, 4 - 20mA, 300Vac double insulation, 13.5bits resolution (<550Ω)
Output 3	0 - 20mA, 4 - 20mA, 300Vac double insulation, 13.5bits resolution (<550Ω)
Output 4	Fully changeover relay contact
Outputs 5 and 6 (VMD)	2 SPST interlocked normally open contacts
Input filter	Off to 59.9s
Zero offset	User-adjustable over the full range
User calibration	Two-point gain and offset
Open wiper detection	>5MΩ

Wiring Instructions

The installation and commissioning instructions supplied with the product specify that safe controller operation requires installation, commissioning, use, and maintenance to be performed properly by suitably qualified personnel. The company’s safety personnel are responsible for ensuring that the product specifications and safety information in the installation and commissioning instructions are understood and followed.