Sequent Microsystems' Latest Board Adds Up to 128 Opto-Isolated Inputs, RS-485 to Your Raspberry Pi

Designed to stack up to eight high, the new board offers fully isolated inputs for up to 240V AC or DC and a handy RS-485 port.

Sequent Microsystems, known for its innovative range of Raspberry Pi add-ons, is back with a new board offering up to 128 fully opto-isolated inputs, and an RS-485 port, on any Raspberry Pi or compatible single-board computer.

"Raspberry Pi can read 26 Input signals through the GPIO [General-Purpose Input/Output] header, but sometimes you might need to read more," explains Sequent Microsystems' Mihai Beffa of the inspiration behind this latest board. "Since all GPIO pins are wired directly to the local processor, some hardware is required to connect them to the real world.

"Sequent Microsystems '16-INPUTS for Raspberry Pi' card has 16 optically isolated digital inputs. Input ranges can be jumper-selected for each channel, from 3 volts to 24 volts or from 24 volts to 240 volts. Inputs can read both DC and AC signals. The card communicates with Raspberry Pi using only the I2C port, leaving all the other 24 GPIO pins available for your use. It has also an RS-485 port, a power LED and a push-button that can be used to shut down the Raspberry Pi."

Sequent Microsystems' latest Raspberry Pi add-on stacks to up to 128 digital inputs per host. (📹: Sequent Microsystems)

While the board itself has 16 inputs, that's not its upper limit: Like other boards in Sequent Microsystems' stable, including the 8-MOSTFET load switcher and Mega-RTD temperature sensor HAT, the new device is designed to be stackable for a total of 128 digital inputs per host Raspberry Pi. All inputs include reverse polarity protection and support for both AC and DC signals, an edge-mounting soft-off power switch, a 3A resettable fuse, and a status LED for power.

The company is aiming the board at those who are looking to safely interface with a range of signals at a low cost. The standard board reward is priced at just $40 including connectors and mounting hardware, with early birds able to pay an extra $5 to receive one of 20 fully-tested prototype versions ahead of the full production run.

Full details are available on the project's Kickstarter campaign page, where the project has already reached its modest funding goal.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire:
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