wikiConfiguration of LES plus v4 RS485
The LES plus v4 (with Intel i5-1235U) of Thomas-Krenn provides two serial ports. These can be operated as RS232 (default) or RS485. This article shows how to adapt the two serial ports from RS232 to RS485.
PIN assignment
The following chart shows the PIN assignment of the signals in RS232 as well as in RS485 mode at LES plus v4:
| PIN | RS232 | RS485 | ||
|---|---|---|---|---|
| RS232 | Description | |||
| 1 | DCD | Carrier detect | TX- |
|
| 2 | RXD | Receive data | TX+ | |
| 3 | TXD | Send data | ||
| 4 | DTR | Data terminal ready | ||
| 5 | GND | Signal ground | GND | |
| 6 | DSR | Data ready | ||
| 7 | RTS | Request to send | ||
| 8 | CTS | Clear to send | ||
| 9 | RI | Ringing indication | ||
Change of settings to RS485
To configure the serial ports to RS485, the described jumper LE1, LE2 and LE3 have to be changed and the BIOS settings as mentioned below have to be adjusted.
Implementation of jumper
The chart shows the jumper settings for COM1 and COM2 for RS232 and RS485 each:
| Serial Port | LE1/LE2/LE3 | Mode | |
|---|---|---|---|
| COM1 | 1-3 | RS232 |
|
| 3-5 | RS485 | ||
| COM2 | 2-4 | RS232 | |
| 4-6 | RS485 |
These two pictures in the gallery show the default settings (both for COM ports in RS232 mode) as well as the settings for RS485 (also for both COM ports):
-
standard settings: COM1 and COM2 placed on RS232 (jumper placed on PINs 1-3 and 2-4 each). -
COM1 and COM2 placed on RS485 (jumper placed on PINs 3-5 and 4-6 - the jumpers are shifted to the left each - see orange marking).
Adjustment of BIOS settings
The following settings have to be adjusted so that both COM ports are configured BIOS-sided on RS485:
- Advanced ‣ IT8659 Super IO Configuration ‣ Serial Port 1 Configuration ‣ Mode ‣ RS485
- Advanced ‣ IT8659 Super IO Configuration ‣ Serial Port 2 Configuration ‣ Mode ‣ RS485
More information
- RS-232 (de.wikipedia.org)
- EIA-485 (de.wikipedia.org)
- RS-485 basics: When termination is necessary, and how to do it properly (e2e.ti.com/blogs)
- RS-485 basics (e2e.ti.com/blogs)
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Author: Werner Fischer Werner Fischer, working in the Knowledge Transfer team at Thomas-Krenn, completed his studies of Computer and Media Security at FH Hagenberg in Austria. He is a regular speaker at many conferences like LinuxTag, OSMC, OSDC, LinuxCon, and author for various IT magazines. In his spare time he enjoys playing the piano and training for a good result at the annual Linz marathon relay.
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