Raspberry Pi and Wireless RS485 Display

Posted by Vytas Sinkevicius on

We decided to push our testing of the wireless 900 MHz RS485 interface to include the new PI-SPI-DIN series.

From Left to Right:

  • PI-SPI-DIN Controller - this module supports the RPI 3 on a DIN rail, has a 9 to 24 VDC power input, RS485, Battery Backed Real Time Clock
  • RS485 to Zigbee converter in a  DIN rail enclosure
  • RS485 to Zigbee converter at the pcb level
  • VP-EC-RDU LCD Dispaly - Modbus RTU, 4 line x 20 character, 9 to 24 VDC Power

Typically, in RS485 Modbus applications, you can attach up to 32 devices (or more depending on the driver chips used) and run cabling up to 4000 feet before having to use a repeater.

Here is the test system before converting to wireless:

Most of the products from VP Process Inc. that have RS485 use a RJ45 connector to carry power and RS485 data. This makes wiring extremely simple, any standard Cat5E jumper cable will work.

To convert from the hard wired RS 485 to the wireless RS845 in the first picture took less than 30 seconds - all the devices are "Hardened" and allow for hot swapping and powering.

In the above test, we wanted to test thoroughly the ability of the RS485 Modbus RTU protocol at 9600 and 19200 Baud to go through 2 converters and maintain RS485 and data integrity. The system passed with flying colours!

A typical application for the above would be: Let's say the application calls for gas detection within a mechanical room and a display showing gas levels has to be displayed outside the entrance door to show safe levels before entering. Using the wireless approach above there would be no need to run wiring conduit through a concrete wall which makes installation for new builds and retrofits very simple.

The PI-SPI-DIN series of product is being released by VP Process Inc this June, 2017.

The other devices can be found at these links:

RS485 to Wireless Converter

VP-EC-RDU Remote LCD Display

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