About
The RS422/RS485 Shield allows you OpenMV Cam to transmit data to an RS422 device or get on a RS485 bus. The YA+ and ZD- are the RS485 bidirectional pins (or RS422 receiver pins) while A+ and B- are the RS422 transmitter pins. The shield seamlessly handles either RS422 or RS485 (you cannot, though, do both at the same time). The transceivers are connected to P4 (TX) and P5 (RX) on your OpenMV Cam. You can disconnect these pins, too, if you don't need them.
Better yet! The shield features a wide voltage range 6-36V input, which is robust to reverse voltage and features robust transient surge protection. Use this input to power your OpenMV Cam from 12/24V power supplies without having to worry about damaging your camera. The wide range voltage supply outputs 5.4V on VIN via an OR'ing diode so that you can power your OpenMV Cam from multiple shields with OR'ing diodes (e.g. all of our dual header column shields).
The shield also features a robust 0-5V ADC input (AIN) that outputs 0-3.3V to your OpenMV Cam on P6. The input is robust to reverse voltage and features overvoltage protection (tested up to +/-36V). By shorting a solder bridge jumper on the board, which supplies a 240 ohm load on the input, you can work in 4-20mA mode. If you don't need the ADC input, you can disconnect it from P6, too.
Finally, the shield features a robust 0-5V digital input/output. The SYN pin is tolerant to reverse voltage (tested with -12V), shorting to ground, and shorting to 12V. By default, SYN acts as a digital input driving P10 in Open-Drain Mode so that you can support input triggering from multiple sources, all driving P10. Alternatively, you can switch SYN to be a digital output driving 0-5V for triggering devices from your OpenMV Cam instead of being triggered by them. So, whatever your use case is for triggering, the shield accommodates. If you don't need the trigger input/output, you can disconnect it from P10, too.
This shield is compatible with all OpenMV Cam models.
Applications
You can use this shield to connect your OpenMV Cam to a Modbus network or a DMX-512 universe, for example. All you need to do is supply code to decode the protocol over the UART in MicroPython.
Specs
- PWR (6V-36V) - Reverse Voltage Tolerant (up to -36V) - provides VIN with 5.4V - up to 600mA Draw
- 0-5V ADC Input with reverse voltage protection and built-in over-voltage clamping
- 0-5V Digital Input/Output support for camera syncing - built-in short circuit protection
- 10 Mb/s RS422 Interface - with filtering - terminated (can be disabled)
- or 10 Mb/s RS485 Interface - with filtering - terminated (can be disabled)
- All external interfaces have robust transient voltage protection
The external pin header is designed to grab 20-24 gauge solid core wire and not fail due to vibration. Once you hook up a circuit using this shield, you can be sure it will not come apart. Please use a flat head 1.0-2.0mm screwdriver to release the spring lock headers if you need to remove a wire.
If you want to use this shield with the stranded wire, we recommend using 22-24 gauge ferrules (here) crimped (here) to your wires before inserting them into the shield.
Power Consumption
- 3ma @ 3.3V from your OpenMV Cam's 3.3V rail
