Raspberry Pi Analog Input Module, 8 Channels 4-20mA Input, RS485, Modbus Interface
NOTE: This model has been discontinued
The VP-EC-8AI is an industrial version Raspberry Pi 8 Channel Analog Input Module by VP Process Inc.
Each input accepts a 4-20 mA Input into a 150 Ohm load resistor. The interface supports RS485 Modbus RTU and plugs directly into the Raspberry Pi's GPIO port (26 Pin). Raspberry Pi versions supported are from the original to the new RPi 3.
The 12 bit Analog to Digital convert (ADC) is the popular Microchip MCP3208 and is controlled via the SPI interface. The dipswitch is read by the GPIO lines, and the UART is driven by the Rx and Tx lines and a RS485 direction line, also from the GPIO lines.
Another feature of the VP-EC-8AI is the 8 channel Green LED's used for status indication. In the test code provided, the channel LED lights if the input mA is above a preset level, typically 2.5 mA.
Power: 12 to 24 VDC
Network: RS485, N81, Modbus RTU Protocol (or other protocols as required by the Raspberry Pi)
Modbus ID: Dipswitch Selectable
Analog Inputs: 8 Channels 4-20 mA into 150 Ohm load, PTC Fuse Protection
Resolution: 12 Bit ADC (MCP3208 A/D Chip, SPI Interface)
Dimensions: 3.4" wide x 6.15" long
Power On: BLUE LED
Analog Input: 1 thru 8: GREEN LED ON when input above 2.5mA (74HC595 Driver)