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'''Documentation notice:''' This technical documentation was independently rewritten from an archived supplier source. Check technical details and commands against the product version and manufacturer documentation before use.

== Summary ==
The Waveshare TTL TO RS422 (B) is an industrial rail-mounted converter that converts TTL signals into balanced differential RS422 signals. It supports full-duplex communication and provides galvanic isolation, surge protection, as well as TVS and ESD protection.

== Related products at JW Tech ==
* [https://shop.jw-tech.eu/p/WSAL23652 WSAL23652 – Rail-mount TTL To RS422 Galvanic isolated Converter, Anti-surge, Multiple Isolation Protection]

== Technical overview ==
* Compatible with the TTL/RS485 standard; converts TTL into a balanced differential RS422 signal and supports full-duplex communication.
* Supports TTL signal levels from 3.3 V to 5 V; the power supply includes reverse-protection and over-voltage circuitry.
* Onboard unibody power-supply isolation delivers stable isolated voltage without requiring an additional external power source for the isolated terminal.
* Onboard unibody digital isolation enables signal isolation with high reliability, strong anti-interference, and low power consumption.
* Onboard TVS (Transient Voltage Suppressor) effectively suppresses surge voltages and transient spikes in the circuit and provides electrostatic discharge (ESD) protection.
* Onboard resettable fuse and protection diodes ensure stable current/voltage outputs, provide over-current/over-voltage protection, and improve shock resistance.
* Connections: TTL side uses screw terminals; RS422 side also uses screw terminals with built-in 120 Ω termination resistors that can be enabled or disabled via jumpers inside the case.
* Transmission distance: TTL under 10 m; RS422 approximately 1200 m; point-to-multipoint operation supports up to 32 nodes (adding relays is recommended beyond 16 nodes).
* Enclosure: Industrial ABS housing designed for a 35 mm DIN rail, dimensions 91.6 × 58.7 × 23.3 mm.
* Operating temperature range: −15 °C to 70 °C; tested at 921600 baud and operates stably; power consumption at 5 V is 0.12 W.

== Notes and version constraints ==
* The product is primarily designed for RS422 devices; using it with RS485 devices is only possible in transmit mode – the TTL TO RS485 (B) model is recommended instead.
* For short-distance communication, the built-in 120 Ω termination resistors can be disabled by setting the jumpers to NC; for long-distance multi-device setups, 120 Ω resistors should be added at the first and last devices on the bus.
* The module only provides a physical-layer hardware converter; parameters such as baud rate or node configuration do not need to be set. Modbus communication must be implemented at the protocol layer.
* Testing requires a USB-to-TTL adapter and a USB-to-RS422/RS485 adapter, which are not included in the delivery scope.
* The exact position and handling of the jumpers for the 120 Ω resistors requires opening the case; detailed steps are missing from the source and require manual verification.

== Source and revision record ==
* [https://www.waveshare.com/wiki/TTL_TO_RS422_(B) TTL TO RS422 (B) - Waveshare Wiki]
* Source revision: 91424
* Captured: 2026-09-04T03:12:44+00:00
* SHA-256: <code>0f29b40d159ba2714ef4f6a3aeae18830b5824ac2b4cc13a72664fac2a54c03b</code>

WSAL23652 – TTL TO RS422 (B)/en - Versionsgeschichte

JWTechPublisher: Freigegebene technische Dokumentation veröffentlicht; Text-only und noindex