Is there a hidden menu (MX1) or other that will do some sort of loopback test on the serial ports of the MX1?
I want to test Serial-4 from the MX1 through the cable to the DB9 going to the iEFIS Extender.
Can't get these two to talk to each other, and have run out of things to check.
RS232 LOOPBACK Test
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Please keep your posts friendly and on topic. No politics or discussions of a controversial nature not related to our favorite subject of flying and avionics. Offending posts may be removed or moderated.
Re: RS232 LOOPBACK Test
RS232 is the flakiest standard ever invented. If you have RX - TX and vice versa connected correctly, correct baud rates and correct protocols set on both ends you are left with 1) cable needs to be screened and grounded at one end only. 2) Ground source between the two devices is different - this will make a huge difference. 3) Faulty UARTS. It is quite easy to buy an RS232 splitter and an RS232 to USB cable. Download some free monitoring software for Apple or Windows, you will also be able to type or paste in Send commands on the software. That way you can see all the expected traffic and see if the hardware does what is expected when it receives . It will come in handy in the future as well - believe me!
David Vale
G-OCAD
Sequoia Falco
MGL user for more than 10 years!! Explorer iEFIS, Discovery Lite, Vega backup & MGL a/p
G-OCAD
Sequoia Falco
MGL user for more than 10 years!! Explorer iEFIS, Discovery Lite, Vega backup & MGL a/p
Re: RS232 LOOPBACK Test
To answer my own question, for the benefit of others, here is how the test mode works. I discovered another MGL owner on the airfield who showed this to me. I suppose MGL has documented this but I don't know where.
Just connect a jumper from Tx to Rx and switch to the 'Serial Port Diagnostics Page'. You can see in the image below that port one is test mode. The "94" you see will be counting up if it is working.
In my case, I was trying to trouble shoot the RS232 between the MX1 (port 4) and iEFIS Extender (port 1). For this test , the connector from the Extender was removed the jumper placed there. This way both the RS232 port and wire harness were tested at the same time. Upon doing this it was very easy to see that the wire and pins were correct and that the RS232 port was active (port 4 in this case). That narrowed down the problem to two possibilities either a bad Extender (which had already tested good) or the pins were reversed.
Although I had carefully checked (ringed out) the connections and checked the pins etc on more than four occasions, on more than one day I went ahead and swapped two pins. Bingo! the Extender now worked. I've not yet confirmed it but it's my suspicion that either the MX1 or the Extender's pins are marked incorrectly. From what I can tell, according to the diagram markings, I'm now wired RS232 port 4 to Extender port 1 as Rx->Rx and Tx->Tx which should not work.
So I've purchased a small cheap ($74) oscilloscope and the next time the MX1 is out of the plane I plane to check to see which pin is actually the Tx pin. If the Rx pin is transmitting then MGL you owe me lunch for two weeks of lost time trying to track this down.
Just connect a jumper from Tx to Rx and switch to the 'Serial Port Diagnostics Page'. You can see in the image below that port one is test mode. The "94" you see will be counting up if it is working.
- RS232-diag.jpg (219.51 KiB) Viewed 2215 times
Although I had carefully checked (ringed out) the connections and checked the pins etc on more than four occasions, on more than one day I went ahead and swapped two pins. Bingo! the Extender now worked. I've not yet confirmed it but it's my suspicion that either the MX1 or the Extender's pins are marked incorrectly. From what I can tell, according to the diagram markings, I'm now wired RS232 port 4 to Extender port 1 as Rx->Rx and Tx->Tx which should not work.
So I've purchased a small cheap ($74) oscilloscope and the next time the MX1 is out of the plane I plane to check to see which pin is actually the Tx pin. If the Rx pin is transmitting then MGL you owe me lunch for two weeks of lost time trying to track this down.