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M90-19-R4 Unitronics RS232 to RS422/RS485 converter
Unitronics M90-19-R4 isolated communication converter for converting RS232 serial communications to RS422 or RS485 networks in industrial automation applications.
£114.54
Why Choose the Unitronics M90-19-R4 Communication Converter?
The Unitronics M90-19-R4 is a robust and reliable RS232 to RS422/RS485 isolated communication converter designed to enable seamless serial communication between PLCs, PCs, HMIs and industrial automation devices. Developed for use with Unitronics controllers and compatible third-party equipment, it provides a simple solution for integrating RS232 devices into industrial communication networks.
Designed for machine builders, system integrators and automation engineers, the M90-19-R4 automatically senses data direction without requiring handshaking, simplifying installation and reducing configuration requirements. Its galvanically isolated design improves communication reliability by protecting connected equipment from electrical noise, ground loops and industrial interference.
Powered by a 24 V DC supply, the M90-19-R4 supports both RS422 and RS485 communication standards, making it ideal for long-distance industrial networks and multi-node PLC communication systems. The compact DIN rail-mounted housing allows straightforward installation inside electrical control panels and automation cabinets.
Key Advantages
- Converts RS232 communication signals to RS422 or RS485.
- Galvanic isolation improves noise immunity and communication reliability.
- Automatic data direction sensing eliminates handshaking requirements.
- Supports both half-duplex and full-duplex communication.
- Compatible with Unitronics and third-party industrial devices.
- DIN rail mounting for control panel installation.
- Supports long-distance industrial communication networks.
Key Features
- RS232 to RS422/RS485 isolated converter.
- Supports RS422 and RS485 communication protocols.
- Automatic transmit/receive switching.
- RJ11 connection for Unitronics controllers.
- Screw terminal connections for network wiring.
- Supports up to 32 nodes on RS485 networks.
- Communication status LED indicators.
- Snap-mount DIN rail installation.
Reliable Industrial Network Integration
The M90-19-R4 enables legacy RS232 equipment to communicate across modern RS422 and RS485 industrial networks. By converting communication standards while maintaining electrical isolation, it helps ensure stable and reliable data transfer in electrically noisy environments.
Its support for long communication distances and multi-node networking makes it particularly suitable for PLC networks, supervisory systems and distributed automation architectures. The automatic direction sensing feature simplifies commissioning while reducing wiring complexity and installation time.
Typical Applications
- Unitronics M90 and M91 PLC communication networks.
- Industrial RS485 multi-drop networks.
- PLC-to-PC communication systems.
- SCADA and supervisory control integration.
- Machine automation systems.
- Building automation networks.
- Industrial serial communications.
- Legacy equipment integration projects.
Technical Specifications
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| Device Type | Protocol Gateway / Converter | |
|---|---|---|
| Product Series | Unitronics M91 | |
| Coil / Supply Voltage | 24 V DC | |
| Communication | RS232, RS422, RS485 | |
| Voltage | 24 V | |
| Product type | RS232 to RS422/RS485 communication converter | |
| Supply voltage | 24 V DC nominal | |
| Operating voltage range | 20.4 to 28.8 V DC | |
| Current consumption | 35 mA maximum | |
| RS232 interface | RJ11 connector and screw terminal | |
| RS422/RS485 interface | Screw terminal block | |
| Maximum RS232 cable length | 15 m | |
| Maximum RS485 cable length | 1200 m | |
| Supported nodes | Up to 32 devices | |
| Supported baud rates | 9600, 19200, 38400 bps | |
| Communication modes | Half duplex and full duplex | |
| Isolation | Galvanic isolation | |
| Mounting type | 35 mm DIN rail | |
| Dimensions (L × W × H) | 110.8 × 22.5 × 75 mm | |
| Weight | Approximately 98 g | |
| Operating temperature | 0°C to 50°C | |
| Storage temperature | -20°C to 70°C |
Frequently Asked Questions
What is the Unitronics M90-19-R4 used for?
The M90-19-R4 converts RS232 serial communication signals to RS422 or RS485, enabling industrial devices and PLCs to communicate across longer-distance networks.
Does the converter support both RS422 and RS485?
Yes. The M90-19-R4 supports both RS422 and RS485 communication standards and can be configured for half-duplex or full-duplex operation.
How many devices can be connected on an RS485 network?
The converter supports RS485 networks containing up to 32 connected nodes when correctly configured.
Does the converter require handshaking?
No. The M90-19-R4 automatically detects data direction and switches transmission direction without requiring handshaking signals.
How is the M90-19-R4 mounted?
The converter is designed for installation on a standard 35 mm DIN rail inside industrial control panels and automation cabinets.
Trusted by Automation Engineers Worldwide
Unitronics communication converters are widely used throughout industry to provide reliable serial communications, PLC networking and seamless integration between legacy equipment and modern industrial automation systems.
