SRM8 Serial Relay Module 8-Channel

Description

SRM8 Serial Relay Module 8-Channel SRM8 is an 8-channel relay module designed to allow expanding microcontroller I/O pins. SRM8 is based on the 8-bit shift register 74595 IC. It supports 8 output relays while using only three I/Os. SRM8 can be daisy-chained to further extend the outputs to theoretically an infinite number while still using the same three microcontroller I/O pins. SRM8 module can be supplied from a wide range of voltages (5-40V). The input control signals are Digital Input (DI), Clock (CK), and Load (LD). Every time the shift register Clock input receives a low to high transition it accepts the data input value to bit0 and shifts the internal register data by one bit. Thus, 8 clock pulses are required to get one-byte data from the microcontroller. Finally, a latch pulse is required to load all internal shift register data to parallel outputs (Relays). This control sequence can be performed using a hardware-implemented SPI or a few lines of written code. Features Supports: 8-channel output relays. Protocol: SPI. Wide operating voltage range: 5-40V (two selectable ranges). Input signals (TTL): Data Input (DI), Clock (CK), and Load (LD). Output signals (TTL): Data Output (DO), Clock (CK), and Load (LD). Power-on relay status is OFF (a reset operation is auto-applied up on power on). Green LED for power indication. Red LED indicator for each output relay. Both normal open and normal close terminals are available. Reverse polarity protection for power input. Input and output signals are available via screw clamp terminals as well as pin headers for flexibility. SRM8 module can be daisy-chained to obtain a large number of relay outputs. The power connector is duplicated to facilitate the daisy chain board-to-board power connection of up to 16 modules, To connect more SRM8 modules use external wiring. Mounting: Four (Ø 3.5mm) mounting holes for easy installation. Dimensions: 207 X 45 X 18mm. Specifications Parameter Value Model SRM8 Channels 8 relay outputs Control Interface Serial (74595 shift register) — DI, CK, LD (SPI compatible) Supply Voltage Wide range 5–40V (selectable ranges) Power Connector Duplicated for easy daisy-chain power up to 16 modules (board-to-board up to 16) Indicators 1× green power LED 8× red relay status LEDs Contact Types NO and NC terminals provided per channel Protection Reverse-polarity protection on power input Signal Access Screw-clamp terminals and pin headers for DI/CK/LD/DO Mounting 4 × Ø3.5 mm mounting holes Dimensions 207mm × 45mm × 18mm Applications Expanding microcontroller or PLC outputs for relay-based switching in automation systems. Controlling lamps, solenoids, motors and HVAC or lighting circuits in test rigs and control panels. Prototyping and classroom projects where many relay channels are needed with minimal wiring. Multi-module installations that require convenient chained expansion and centralized power distribution. Any low-voltage control system needing reliable, screw-terminal relay outputs. Package Contents 1× SRM8 Serial Relay Module 8-Channel.

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