Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I have a device, namely a Synology DiskStation. It has a 3.3V RS232 interface on board. All I have is a 5V RS232 to USB adapter. Can I attach it to my DiskStation without making any smoke?

share|improve this question

2 Answers 2

up vote 5 down vote accepted

I'm not an electronics expert but everything I've ever read about attaching serial ports to boards that have 3.3v UART pads says to use a TTL converter, or convert the voltage somehow. So I believe you really need something to convert to the proper voltage.

You might get away with it if you only use it to receive serial data from the UART, but I wouldn't chance it.

share|improve this answer

The RS232 standard specifies +/- 3-15V

If any device is advertised as RS232 and emits smoke when presented with a valid 15V RS232 signal, I'd say it is suffering from a manufacturing defect which the manufacturer should rectify at no cost to you.

"RS-232 drivers and receivers must be able to withstand indefinite short circuit to ground or to any voltage level up to ±25 volts." - Wikipedia

You could always ask the manufacturer?

Update:

The serial port on a Synology NAS is not RS232.

"The serial port on Synology NAS boxes is using 3.3V TTL levels, which have to be converted into regular RS232 levels by a level shifter circuit." - NetBSD

share|improve this answer
    
RS232 is specified +- 3-15V, but actually this is only true for computers. Things like embedded devices often have levels of +- 3.3V and +-5V. –  Max Ried Jun 14 '11 at 14:23
    
If it doesn't produce at least +/-5V it isn't RS232. If it doesn't accept +/-25V it isn't RS232. This applies to embedded devices, not just to computers. –  RedGrittyBrick Jun 14 '11 at 14:33
1  
Paper doesn't blush. This might be the standard, but in real world, most current devices that have a "RS232" interface, speak "RS232" logically, but downscaled +-3.3V or +-5V. So it might no be entirely technically correct to speak of RS232, but it's common speak. –  Max Ried Jun 14 '11 at 14:48
    
@bot47: Yes I accept what you say. However if a consumer device presents a DB-25, DE-9 or even modular-socket and it's manual says you can connect RS232, it is reasonable to expect that this can be connected to a +/-15V RS232 device. If (as may be the case here) it has a 6-pin header on a circuit board not normally accessible to end users, it is not a safe assumption. In the latter case the question arguably belongs on electronics.stackexchange.com –  RedGrittyBrick Jun 14 '11 at 16:10

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.