> Anyone has experience making Raspberry Pi talking with server via RS232 serial interface?
I have:
- two Dell R710
- Raspberry Pi 3
- Raspberry Pi 4
- Several x86 machines
- StarTech.com USB to RS232 DB9 serial adapter [0]
- RS232 serial header adapter [1]
- DB9 cable [2]
The StarTech.com USB adapter seems to work well. I haven't had any trouble with it whatsoever.
I will say that I'm very unimpressed with serial interfaces in general but especially of Dell's BIOS output. Sure, they're aged... but serial is aged way older. Dell's firmware would often write to parts of the 80x24 screen which were already displaying something else and make it practically impossible to read what's going on. It seemed to especially occur when starting different sections of hardware. When the Dell firmware would start up, it would fill the interface with a text-display showing status and what's about to load. It would offer "press key to configure". When it goes to load drivers for netboot/disk/etc, it wouldn't clear the screen. Netboot would write its output on top of the "press key to configure" interface. Then drivers for the disk would write on top of _that_. Further, the configuration interface would sometimes wrap some of the fields to the next line and garble that line. And finally, the interface simply _didn't work at all_ if it wasn't at 9600baud. So input/output slow af. And the text would all be garbled if the serial bit rate were misconfigured with regards to 7/8 data/parity or check bits or etc (but that's to be expected). The problems with Dell's BIOS output to serial are difficult enough to work with that I would not try to use it to try to debug it outside of academic exercise. My time's worth more than that.
On the other hand, I have used it work with the bootloader (grub) before the kernel has loaded. I successfully used the serial interface to diagnose and repair a driver problem with a video card on an desktop that I had. I had a straight DB9 cable connected to a pair of motherboards who had serial interface headers. I'd connected a header adapter and a straight DB9 cable and encountered a lot of the same problems. That was a fun, albeit trying, experience because it involved a lot of reboot cycles which are quite time consuming. There were still a lot of similar problems with regards to overwriting parts of the interface that hadn't been cleared but they weren't nearly as numerous as with Dell's BIOS output.
I have:
- two Dell R710
- Raspberry Pi 3
- Raspberry Pi 4
- Several x86 machines
- StarTech.com USB to RS232 DB9 serial adapter [0]
- RS232 serial header adapter [1]
- DB9 cable [2]
The StarTech.com USB adapter seems to work well. I haven't had any trouble with it whatsoever.
I will say that I'm very unimpressed with serial interfaces in general but especially of Dell's BIOS output. Sure, they're aged... but serial is aged way older. Dell's firmware would often write to parts of the 80x24 screen which were already displaying something else and make it practically impossible to read what's going on. It seemed to especially occur when starting different sections of hardware. When the Dell firmware would start up, it would fill the interface with a text-display showing status and what's about to load. It would offer "press key to configure". When it goes to load drivers for netboot/disk/etc, it wouldn't clear the screen. Netboot would write its output on top of the "press key to configure" interface. Then drivers for the disk would write on top of _that_. Further, the configuration interface would sometimes wrap some of the fields to the next line and garble that line. And finally, the interface simply _didn't work at all_ if it wasn't at 9600baud. So input/output slow af. And the text would all be garbled if the serial bit rate were misconfigured with regards to 7/8 data/parity or check bits or etc (but that's to be expected). The problems with Dell's BIOS output to serial are difficult enough to work with that I would not try to use it to try to debug it outside of academic exercise. My time's worth more than that.
On the other hand, I have used it work with the bootloader (grub) before the kernel has loaded. I successfully used the serial interface to diagnose and repair a driver problem with a video card on an desktop that I had. I had a straight DB9 cable connected to a pair of motherboards who had serial interface headers. I'd connected a header adapter and a straight DB9 cable and encountered a lot of the same problems. That was a fun, albeit trying, experience because it involved a lot of reboot cycles which are quite time consuming. There were still a lot of similar problems with regards to overwriting parts of the interface that hadn't been cleared but they weren't nearly as numerous as with Dell's BIOS output.
[0]: https://www.newegg.com/p/N82E16812400121
[1]: https://www.newegg.com/startech-icusb232int1-usb-to-db9/p/N8...
[2]: https://www.newegg.com/p/12K-01CJ-00009