Hi all,
Not sure if there are any electronics nerd out there. I need some help tracking down a USB to RS232 cable. I have a raspberry pi and I need it to connect to a serial device. I tried some cables out there from Jaycar and RS Components, but none seems to work. I finally figured out that it is due to most cable these days only convert the signals to 0-5V(TTL) instead of +-12V which my picky serial device requires.
Do you know if any USB to RS232 cables that has +-12V output?
Thanks.
The cable I'm talking about is the one elusive has linked to below. The wires on the other end would connect to the Rx and Tx pins on your Pi
You could also get a RS232 <=> TTL converter, e.g. https://www.sparkfun.com/products/449 - there's probably cheaper on eBay; this one might work.
Could you pose a link so I can have a look at the product you have owned?
Well, there are quite a few of chips provides you with USB<—->TTL conversion and you need a cable with RS232 capabilities. Some of the sellers refer this to a dual chip USB to RS232 cable (which converts to 5V TTL first, then use MAX232 or MAX3232 chip to do a little bit boost conversion to +/- 12V).
Also be aware that most of the USB to RS232 chips are emulators based which means there is no hardware IRQ reserved for most of these product. It would cost you a fortune if you buy a "real" hardware based module. But these cheap cables will do the work most of the time.
PS: I am a hobbyist of electronics. I got small lab at home.
It's a Somfy blinds hub. Do you know if any of the MAX3232 cables do that? I see a lot of people selling USB to serial cables, but none actually specify whether the output is +-12V.
I don't really need full duplex communication. I just need to send commands to the Somfy blinds hub from the RPi.
PS. I would love to setup my own lab at home. Just not allowed. Lol. A oscilloscope would be nice. Do you have one? I am thinking of turning one of my old laptops into a digital oscilloscope. I think there are USB ones that I can buy.
Are you trying to output from the USB ports on the Pi? dont think you can do it that way, use the Rx and Tx pins on the Pi, then get some sort of cable / converter that will convert from that to RS232 serial cable (if it exists).