RPi 3, Pi-SPi-RS485 and Gas Sensors

The brand new Pi-SPi-RS485 Interface has just arrived and I had to take it for a spin with some of our products. Here is a pic of my test setup:

From left to right: RPI 3, Pi-SPi-RS485, VP-TX100-CO Transmitter complete with MQ3 solid state sensor, and the Modbus VP-RDU Display.

The Pi-SPi-RS485 has some pretty cool features like dual GPIO ports for easy expansion, dual terminal blocks and dual RJ45 jacks for Cat5e cable connections. The wiring for the RJ45 is printed right on the board, and power for remote devices like the display is carried over the Cat5e cable.

Another feature of the Pi-SPi-RS485 is the remote Field Power Input - the only connection is the GND between the field power and the RPi power. Also the module has it's own LDO 3.3V regulator to minimize loading on the Pi's power supply.

Since both transmitter and display have RS485 and Modbus IO capability, the maximum distance between the two (with the Pi-SPi-RS485 and RPi 3 in between, more or less) can be up to 4000 feet - that's almost a mile!. All the RS485 drivers used in these products have ESD protection as a standard features.

The footprint of the Pi-SPi-RS485 is identical to the RPi 3, allowing for some flexible mounting as shown in these pics:

The dual GPIO ports on either side of the module allow for easy expansion for other modules.

More information on the Pi-SPi-RS485 can be found at:


Finally, this unit is offered in kit form with all the SMD parts already mounted, all the user has to do is solder on the through hole components. The unit is also offered fully assembled and factory tested.

More modules coming very, very soon!







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