WSAL23778 – TTL TO RS485 (B)/en

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 rail-mount TTL-to-RS485 converter converts TTL signals into balanced differential RS485 signals and supports half-duplex communication over up to 1200 m. It provides 600 W lightning protection, 15 kV ESD protection, TVS surge suppression, and a switchable 120 Ω termination resistor.

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• WSAL23778 – Rail-mount TTL To RS485 Galvanic isolated Converter, 600W Lightningproof & Anti-Surge, Multi-Isolation Protection

Technical overview

• Galvanically isolated TTL-to-RS485 converter for DIN-rail mounting on a 35 mm DIN rail.
• Compatible with the TTL/RS422 standard; supports half-duplex communication.
• Input level: 3.3 V to 5 V TTL; the power input includes reverse-connection and over-voltage protection circuits.
• Mounting: ABS case with DIN-rail clip, dimensions 91.6 × 58.7 × 23.3 mm.
• RS485 side: screw terminals, transmission distance approx. 1200 m, point-to-multipoint operation supporting up to 32 nodes (repeaters recommended for 16 or more).
• Integrated 120 Ω resistor with a toggle switch: up = enabled, down = disabled.
• Protection circuits: TVS against transients, resettable fuse, protection diodes for over-current and over-voltage.
• The Modbus protocol must be implemented at the protocol layer; the module itself is only a voltage/signal converter with no built-in parameter configuration.

Notes and version constraints

• The maximum stop-bit setting depends on the connected devices; if communication fails, disable the 120 Ω resistor by flipping the switch down.
• When using 16 or more RS485 nodes, insert a repeater to maintain signal integrity.
• The exact current draw varies with operating state; the stated average value (0.054 A at 5 V) applies only under defined test conditions.
• Before commissioning, verify whether the RS485 endpoint requires a GND connection; ground it if necessary.
• Because RS485 is half-duplex, transmitting and receiving cannot occur simultaneously; factor this into system design.

Source and revision record

• TTL TO RS485 (B) - Waveshare Wiki
• Source revision: 87643
• Captured: 2026-09-04T03:29:24+00:00
• SHA-256: 8af5ac738b745fa05fec02d2ba392944475c9d13e20adcb0a8136323ddb64828