Miniature Pyrometer with RS-485 Modbus for Multi-Channel Systems

Sensor Features

  • Miniature non-contact temperature sensor
  • RS-485 Modbus interface
  • Measures temperatures from -20°C to 1000°C
  • For use in ambient temperatures of up to 120°C without cooling
  • Compatible with third-party RS-485 Modbus Master devices, or Calex touch screen interface
  • Not designed or approved for fever detection

PM180 Touch Screen Interface Features

  • 6-channel temperature display with configuration, alarms and data logging
  • Analogue and alarm relay outputs via optional modules

System Features

  • Low-cost standalone 6-channel temperature measurement system
  • Build larger systems using the PM180’s separate Modbus Master and Slave interfaces
  • Connect PyroMiniBus sensors directly to third-party RS-485 Modbus systems

For specifications of the PM180 touch screen interface, see PM180

General Specifications

Temperature Range
-20°C to 1000°C
RS-485 Modbus RTU
±1% of reading or ±1ºC whichever is greater
± 0.5% of reading or ± 0.5°C whichever is greater
0.2 to 1.0
Response Time, t90
125 ms (90% response)
Spectral Range
8 to 14 μm
Supply Voltage
6 to 28 V DC
Supply Current
50 mA max.
Baud Rate
9600 baud (other configurations available upon request)
Modbus Data Format
8 data bits, no parity, 1 stop bit (other configurations available upon request)


Configuration Method
Via PM180 touch screen, or directly via RS-485 Modbus
Configurable Parameters
Emissivity Setting, Averaging, Peak/Valley Hold Processing, Reflected Energy Compensation

Field of View Diagrams

Please note: The given measured spot size contains 90% of the energy detected by the sensor. We normally recommend the target is at least twice as large as the given measured spot for maximum accuracy. Sensors may be used at longer distances than the above diagrams show. There is no maximum measurement distance in clean air; this is because the PyroMiniBus detects only the wavelengths of infrared radiation that are not absorbed by the atmosphere.

Mechanical Specifications

Stainless Steel
18 mm diameter x 45 mm long (excluding cable gland)
Thread Mounting
M16 x 1 mm pitch
Cable Length
1m (longer lengths available to order)
Weight with Cable
85 g

Environmental Specifications

Environmental Rating
Ambient Temperature Range
PyroMiniBus sensor: 0°C to 120°C including cable
PMBHUB junction box: 0°C to 80°C
Relative Humidity
95% max. non-condensing

Electromagnetic Compatibility Standards

EN61326-1, EN61326-2-3 (Electrical Equipment for Measurement, Control and Laboratory Use – EMC Requirements – Industrial)

The PyroMiniBus may be installed as a new temperature monitoring system, or integrated into an existing Modbus network with third-party hardware.

With two Modbus interfaces, the PM180 touch screen module makes an ideal local display for a group of sensors as part of a larger system.

The PMBHUB junction box makes it easy to connect the system together.

Never miss a critical temperature event. In condition monitoring applications, the PyroMiniBus system is an always-on solution that can replace manual checks with a handheld thermometer or expensive thermal imager.

For example, some typical uses include:

Typical Applications

Power distribution
Monitor the temperature of busbar joints in switchgear cabinets. Hundreds or even thousands of points can be monitored on the same network using PyroMiniBus sensors.
Curing ovens
Fibreglass impregnated with epoxy is cured in an oven to increase strength. PyroMiniBus sensors are placed inside the oven at up to 120°C, to build up a temperature profile at many points on the entire surface of the workpiece, and to communicate the measured temperature to the heating system that controls the hot air blowers in the oven. Industries include boatbuilding and aerospace as well as many others.
Industrial bakery
Check the temperature profile of bakery products at multiple points along a conveyor oven.
Corrugated board manufacturing
Monitor the web temperature along an entire corrugator, with local displays for each section of the production line, and centralised monitoring in the control room. Sensors withstand 120°C, and can be used in high-temperature areas such as single facers without cooling.
A large system of PyroMiniBus sensors can monitor the paint curing process at several points.
Monitor temperatures around the entire vehicle in environmental test chambers.
Condition monitoring
A network of PyroMiniBus sensors can monitor all the bearing temperatures on a machine, a runout table, or the whole factory. The PyroMiniBus is ideal for measuring the temperature of all painted metal surfaces.
Infrared curing
Arrays of sensors fitted on a rig of infrared curing lamps ensure an even temperature profile along the part being cured. Surface coatings, paint and epoxy are ideal target materials, among many others.
Gas cylinder filling
Monitor temperatures to improve repeatability in the filled volume and improve filling efficiency. The temperature of every cylinder on a filling rig is easily monitored with no need to manually move contact probes.

PyroMiniBus sensors are compatible with third-party RS-485 Modbus Masters. The standard data format is 9600 baud, 8N1. Contact Calex for other requirements.

Calex also provides the 6-channel PM180 touch screen display/configuration module for up to 6 sensors.

Connect up to 247 PM180 sub-networks or individual PyroMiniBus sensors directly to another Modbus network via the PM180’s Modbus slave interface.

The PMBHUB junction box is designed for use with PyroMiniBus sensors. It is also compatible with PyroMini and FibreMini sensors via a suitable cable.

Electrical Installation

Wire colour codes for PyroMiniBus sensors

Dimensions (mm)

PM180 6-Channel Hub

6-channel touch screen hub for temperature display, alarms, configuration and data logging. Isolated RS-485 Modbus master and slave interfaces allow multiple hubs to be connected to a larger network. Optional modules provide analogue and relay outputs. Surface mounting.

Pixsys STR571

The STR571 is a configurable 8-variable Modbus indicator.

For example, you could configure the unit to display the measured temperature from 8 sensors, or the sensor temperature and the measured temperature for 4 sensors, and so on.

The STR571 is compatible with all Calex Modbus infrared temperature sensors, and other Modbus devices.

Full specifications: Pixsys STR571

Air Purge Collar

The air purge collar is used to keep dust, fumes, moisture and other contaminants away from the lens. Air flows into the fitting on the side and out of the aperture at the front.

Fixed Mounting Bracket

The L-shaped fixed mounting bracket offers a rigid support for the sensor and allows fine rotational adjustment about one axis.

Adjustable Mounting Bracket

The adjustable mounting bracket consists of a fixed mounting bracket plus another L-shaped bracket. When assembled as shown, the adjustable mounting bracket offers a rigid support for the sensor and allows fine two-axis adjustment.

Gooseneck Mount

This stiff, self-supporting steel gooseneck for Calex sensors can be attached securely to machinery via a robust aluminium mounting block.

Simply grab the sensor, move it, and the gooseneck will hold it in position. It is the quickest, easiest way to adjust the aim of the sensor.

Gooseneck Mount Data Sheet (

Laser Sighting Tool

The Laser Sighting Tool screws onto the front of the sensor during installation and shows precisely where the sensor is aiming. Once the sensor has been aimed at the centre of the target and locked in position, the Laser Sighting Tool can be removed. The laser is operated via a latching push button on the front of the tool.

Data Sheet / Operator’s Guide (PDF)

Protective Plastic Window

When fitted over the lens of the sensor, the protective plastic window in stainless steel holder provides mechanical protection and helps retain fragments of lens in case of damage. Adjust the sensor’s emissivity setting to compensate for the presence of the window for maximum accuracy. This accessory is ideal for the food and pharmaceutical industries.

Operator’s Guide – Protective Windows


PyroMiniBus Infrared Temperature Sensors

Model Description
PyroMiniBus infrared temperature sensor with direct RS-485 Modbus RTU communications and:
PMB21 2:1 (wide-angle) divergent optics
PMB201 20:1 (general-purpose) divergent optics
PMBXCF Close-focus optics (3.5 mm spot diameter at 50 mm distance)

Touch Screen Interface Module (optional)

Model Description
PM180 6-channel touch screen terminal with temperature display, alarms, sensor configuration and data logging for up to 6 PyroMiniBus, PyroMini, PyroBus or FibreMini sensors. Separate RS-485 Modbus Master and Slave interfaces.

Junction Box (optional)

Model Description
PMBHUB Wall-mounted IP65 junction box for PyroMiniBus. Allows up to 6 sensors to be easily connected to a PM180 via the included 8 cable glands and removable screw terminals.

Output Modules (optional)

Model Description
M-7061-D-G-CR Relay output module for PM180 touch screen terminal, 12 channel, DIN rail mounted. Each relay can be assigned to any alarm via the PM180 interface.
M-7024-G-CR Analogue output module for PM180 touch screen terminal, 4 channel, DIN rail mounted. Each output can be assigned to any measured temperature.