RS-485 Framework Expansion Card
This Framework laptop expansion card will show up on your system as a serial device up to 3,000,800 baud rate. RS-485 equipment connects to its JST XH connector or just by using standard 0.1" jumper cables. Adapter allow for non-isolated RS-485 half-duplex communication with automatic transmit control and 120Ω termination. Also provided is 5V 100mA current-limited output.
The following baud rates are supported:
| Baud rate | Actual | Error | Divisor |
|---|---|---|---|
| 300 | 300 | 0.00% | 10000.000 |
| 600 | 600 | 0.00% | 5000.000 |
| 1,200 | 1,200 | 0.00% | 2500.000 |
| 1,800 | 1,800 | 0.00% | 1666.625 |
| 2,400 | 2,400 | 0.00% | 1250.000 |
| 4,800 | 4,800 | 0.00% | 625.000 |
| 7,200 | 7,201 | 0.01% | 416.625 |
| 9,600 | 9,600 | 0.00% | 312.500 |
| 14,400 | 14,406 | 0.04% | 208.250 |
| 19,200 | 19,200 | 0.00% | 156.250 |
| 28,800 | 28,812 | 0.04% | 104.125 |
| 38,400 | 38,400 | 0.00% | 78.125 |
| 57,600 | 57,692 | 0.16% | 52.000 |
| 115,200 | 115,385 | 0.16% | 26.000 |
| 230,400 | 230,769 | 0.16% | 13.000 |
| 460,800 | 461,538 | 0.16% | 6.500 |
| 921,600 | 923,077 | 0.16% | 3.250 |
| 1,000,000 | 1,000,000 | 0.00% | 3.000 |
| 2,000,000 | 2,000,000 | 0.00% | 2.000 |
| 3,000,000 | 3,000,000 | 0.00% | 0.000 |
All units are hand-soldered, tested for functionality, and enclosed in 3D printed case. For more details you can check blog post describing the earlier version of a device. While this post describes earlier version of PCB, the only significant difference is absence of 5V power supply.
| Price: | $35 order |
| Shipping: | Free within continental USA |
| Package content: | 1x Expansion card |
| 1x 4-pin JST XH female to Dupont jumper cable |
Please note this adapter is not isolated, so do be careful to correctly connect devices, especially if they are connected to a separate power supply. If in doubt, disconnect the AC power before testing connection as this will allow laptop's ground to "float".