Do I need series resistor on RS-232 line?

[N21HV]

I remember seeing somewhere that if I am connecting a non-Dynon avionics to RS-232 line, I need to install a series resistor on the RX line on Dynon side. Did I dream that up? I cannot find any reference to this on the installation manual but before I let the magic smoke out of my unit, I wanted to check.

Hiroo

 

[jakej]

Maybe you're referring to the inline resistor from a certified Gps (eg Avidyne) to the Dynon Transponder (pin3) RX input ?

 

[Garrett]

It is connected between pin 3 rx on my Dynon SV-261 Transponder and the rs232 ADS-B out on my GTN-650. The installation manual says this must be installed.

 

[N21HV]

I am aware of the manual stating the 1.21K resistor is needed for connecting the SV-261 to GPS unit. I do not see any similar notation regarding connecting a COM radio (SL40) to the COM port of the IDU. (The brown / yellow wire with violet and orange stripes). That is what I am talking about.

 

[Dynon]

Yeah, that's the only place in an RS-232 connection where a resistor is used in a SkyView installation.

 

[N21HV]

O.K. So, to confirm explicitly, I will not fry something by directly connecting SL40's TX line to the RX line in the Dynon HDX IDU.

 

[jakej]

Correct - if you are using one of the HDX serial ports then you are good to go