Just tried to use one of the FTDI232 USB to serial interfaces and it didn't work for me. I believe it's because the device I'm trying to connect wants true RS-232 levels and not the TTL levels of this interface.
I know I can make my own interface with a MAX23x, but since I don't have any handy, I was wondering if there was something cheap on Ebay or Ali that would do the trick all-in-one?
I know I can make my own interface with a MAX23x, but since I don't have any handy, I was wondering if there was something cheap on Ebay or Ali that would do the trick all-in-one?
A true RS-232 has +/- 3 to 15V levels, so an active device with external power will be necessary.
I had a similar problem, and it turned out my USB/serial adapter with a "Prolific" PL2303 chip was fake... There are adapters also with fake FTDI chips around...
I had a similar problem, and it turned out my USB/serial adapter with a "Prolific" PL2303 chip was fake... There are adapters also with fake FTDI chips around...
They do vary a lot. I've had luck with some and no luck with others. And the drivers aren't always the best. Sorry not to be of help. 🙁
USB to2 RS232C
A quick search on ALI show those products, some of them have positive evaluations :
Pl2303hxd Android usb hote rs232c cable serie db9f pour hotel iptv android tv smart tv cable de commande console kable | AliExpress
ORIGINAL/authentique pour BUFFALO BSUSRC0605BS FTDI USB cable serie USB vers d sub 9 broches USB vers RS232 convertisseur 0.5 m | AliExpress
Pl2303ra usb rs232c pour cabler le cable serie ouvert d'extremite | AliExpress
A quick search on ALI show those products, some of them have positive evaluations :
Pl2303hxd Android usb hote rs232c cable serie db9f pour hotel iptv android tv smart tv cable de commande console kable | AliExpress
ORIGINAL/authentique pour BUFFALO BSUSRC0605BS FTDI USB cable serie USB vers d sub 9 broches USB vers RS232 convertisseur 0.5 m | AliExpress
Pl2303ra usb rs232c pour cabler le cable serie ouvert d'extremite | AliExpress
I was fed up with such incompatibility when I was about to do a firmware upgrade on a router. I tried several USB/RS232 adapters, neither did work. At the end I used an Arduino micro as a simple USB-Serial converter. It worked flawlessly.
The FTDI devices are good. Make sure you get the right one (they come with "normal" or TTL levels).
These are good, too: WuT Datenblatt: USB <> RS232 Interface Cable 2
These are good, too: WuT Datenblatt: USB <> RS232 Interface Cable 2
Are you sure the issue is the voltage levels? Many USB->Serial converters only translate RXD and TXD. Maybe your equipment is expecting the other control signals as well.
You may be able to trick it into submission with a null modem with loopback handshaking where you un-cross TXD and RXD. Like this:
On each connector, connect DTR, DSR, and DCD together. Those would be pins 1,4, and 6.
On each connector, connect RTS and CTS together (pins 7,8).
Then between the two connectors in the "serial" cable, connect pin 2 to pin 2 (RXD) and pin 3 to pin 3 (RXD).
Pin numbers refer to the DB9. For DB25 Pin numbers, you'll have to dig a little deeper.
Tom
You may be able to trick it into submission with a null modem with loopback handshaking where you un-cross TXD and RXD. Like this:
On each connector, connect DTR, DSR, and DCD together. Those would be pins 1,4, and 6.
On each connector, connect RTS and CTS together (pins 7,8).
Then between the two connectors in the "serial" cable, connect pin 2 to pin 2 (RXD) and pin 3 to pin 3 (RXD).
Pin numbers refer to the DB9. For DB25 Pin numbers, you'll have to dig a little deeper.
Tom
Thanks Tom. I am familiar with RS-232, did some professionally long ago.
Don't have any fancy analysers, but I suspect level is the culprit. I tried the device on a desktop with serial DB-9, and it worked properly. The FTDI I have is a bare PCB, and so I wired all 9 connections to a DB-9 per PC side pinout. That's not a guarantee but I think the most likely thing to check.
Don't have any fancy analysers, but I suspect level is the culprit. I tried the device on a desktop with serial DB-9, and it worked properly. The FTDI I have is a bare PCB, and so I wired all 9 connections to a DB-9 per PC side pinout. That's not a guarantee but I think the most likely thing to check.