8-Channel Serial Relay Module

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.