[maus92]

I installed the GPS 20A position sensor this afternoon, as well as updated the GDU460 software to v 3.80. I did a test run to make sure everything was communicating and LRUs were updating properly. Partially successful, as the pitch servo is in a loop trying to update its software (I have the video.) Might be a CANBUS problem since the pitch servo was the last device in the chain until the GPS 20A was installed. I removed the jumper between pins 3 & 4, which un-terminates the GSA 28, extended the CANBUS line to the GPS 20A and installed the DB9 CANBUS terminator. I get green LEDs on the GPS 20A, and the network error rate is 0% on both the GPS 20A and the pitch servo (although just after the servo software fails to update, it shows a network error rate of ~40%, which rapidly declines to 0%.)

Anyway, my main question is about the proper settings for the GPS 20A for position integrity purposes. In configuration mode, the GPS page makes no mention of the GPS 20A. In the Transponder page, the position integrity selections are "VFR GPS" and I *think* 1e-3," "1e-5" and "1e-7." It's unclear which selection I should choose, but I'm thinking it should be "1e-7." Are there any other setting to be made / changed?

I did notice that on the INFO page when in normal mode, there is some wording that suggests that an external GPS is feeding the signal strength data. Is the GPS source selectable, or does the G3X system select the best source automatically?

Finally, can the G3X peeps give us an idea about what info is transmitted via the CANBUS, and the RS-232 line? My assumption is that ADSB+ formatted data goes directly to the transponder via the RS-232 line, and the CANBUS carries another flavor of data for use with the navigation functions of the GDUs, and the ability to update unit software.

 

[g3xpert]

I installed the GPS 20A position sensor this afternoon, as well as updated the GDU460 software to v 3.80. I did a test run to make sure everything was communicating and LRUs were updating properly. Partially successful, as the pitch servo is in a loop trying to update its software (I have the video.) Might be a CANBUS problem since the pitch servo was the last device in the chain until the GPS 20A was installed. I removed the jumper between pins 3 & 4, which un-terminates the GSA 28, extended the CANBUS line to the GPS 20A and installed the DB9 CANBUS terminator. I get green LEDs on the GPS 20A, and the network error rate is 0% on both the GPS 20A and the pitch servo (although just after the servo software fails to update, it shows a network error rate of ~40%, which rapidly declines to 0%.)

Anyway, my main question is about the proper settings for the GPS 20A for position integrity purposes. In configuration mode, the GPS page makes no mention of the GPS 20A. In the Transponder page, the position integrity selections are "VFR GPS" and I *think* 1e-3," "1e-5" and "1e-7." It's unclear which selection I should choose, but I'm thinking it should be "1e-7." Are there any other setting to be made / changed?

I did notice that on the INFO page when in normal mode, there is some wording that suggests that an external GPS is feeding the signal strength data. Is the GPS source selectable, or does the G3X system select the best source automatically?

Finally, can the G3X peeps give us an idea about what info is transmitted via the CANBUS, and the RS-232 line? My assumption is that ADSB+ formatted data goes directly to the transponder via the RS-232 line, and the CANBUS carries another flavor of data for use with the navigation functions of the GDUs, and the ability to update unit software.

Hello Charley,

There is nothing to configure on the GPS 20A. Just connect it and let it go to work.

Set the GTX23ES position integrity to 1E-7 when using any FAR 91.227 compliant position source like the GPS 20A, GNS 4XXW/5XXW, or GTN 6XX/7XX.

Enable ADS-B Transmit, set ADS-B UAT IN and ADS-B 1090ES IN to Supported, and enable Enhanced Surveillance. Make sure to set all the other Mode S parameters like antenna offset (from nose) and aircraft length/width/size/type/etc shown on pages 31-123,124.

There is no user selection necessary for the position source. Everything recognizes the presence of the GPS 20A and uses this data when it is available and has a strong fix.

You are correct about the uses for the GPS 20A CAN and RS-232 lines.

Best to contact us via email if you would like assistance troubleshooting communication issues.

Thanks,
Steve

 

[maus92]

This morning I was able to coax the pitch servo to update its software - possibly by reseating the connector and tightening the thumbscrews down pretty hard. I did discover that the CWS switch was reading "Low" when it should be "Open." If I pressed the CWS switch, the network error rate jumped, but the "Open" value would only display occasionally. If I pressed the switch rapidly, I could fail the servos (they come back after recycling AP power.) I disconnected the pitch servo entirely because that's the one I touched, but the CWS switch still read "Low." I disconnected the stick and tested the switch itself, which was functioning BUT one conductor was also grounding to the stick itself which is likely to be at least one of my problems..

Anyway, question for the G3X guys: could the "Low" CWS state been interfering with the servo updating its software, or was it more likely to be the reseating / tightening the connector? Note that roll servo updated without drama.

UPDATE: the end of the stick was shorting against the terminals of the CWS switch when the grip screws are torqued tightly. Only took 1/2 of a turn to "correct" the problem, but I'll be doing some surgery to trim off about 1/8" of the stick end. This should correct my issues. Funny that I had tested the stick switches earlier this summer, and they worked properly.

 

[kai]

While I was updating to V 3.80 I pressed the CWS button and the pitch servo failed to update. The update started again automatically and passed ( this time I didn't press the button). I'm prettty sure that this caused your failure.

 

[g3xpert]

This morning I was able to coax the pitch servo to update its software - possibly by reseating the connector and tightening the thumbscrews down pretty hard. I did discover that the CWS switch was reading "Low" when it should be "Open." If I pressed the CWS switch, the network error rate jumped, but the "Open" value would only display occasionally. If I pressed the switch rapidly, I could fail the servos (they come back after recycling AP power.) I disconnected the pitch servo entirely because that's the one I touched, but the CWS switch still read "Low." I disconnected the stick and tested the switch itself, which was functioning BUT one conductor was also grounding to the stick itself which is likely to be at least one of my problems..

Anyway, question for the G3X guys: could the "Low" CWS state been interfering with the servo updating its software, or was it more likely to be the reseating / tightening the connector? Note that roll servo updated without drama.

UPDATE: the end of the stick was shorting against the terminals of the CWS switch when the grip screws are torqued tightly. Only took 1/2 of a turn to "correct" the problem, but I'll be doing some surgery to trim off about 1/8" of the stick end. This should correct my issues. Funny that I had tested the stick switches earlier this summer, and they worked properly.

Hello Charley,

It sounds like you got to the root of at least some, if not all, of the issues, but we wanted to answer your question.

The CWS/DISC input discrete is not sampled during code loads, so should have no impact on this. We did some testing this morning to see if we could interrupt a code load to a servo by continuously pressing/releasing the CWS/DISC button, and we could not. The code loaded just fine.

We recommend you shut down the system and remove the connector from the pitch servo and meter between the CWS/DISC pin and the CAN bus pins while you push the CWS/DISC button to make sure that there is no continuity between these.

You might also carefully inspect the connectors and pins on both sides of this servo connection to make sure that all are properly seated. A backed off pin might explain the need to re-secure the connector as described.

Thanks,
Steve

 

[maus92]

Hello Charley,

It sounds like you got to the root of at least some, if not all, of the issues, but we wanted to answer your question.

The CWS/DISC input discrete is not sampled during code loads, so should have no impact on this. We did some testing this morning to see if we could interrupt a code load to a servo by continuously pressing/releasing the CWS/DISC button, and we could not. The code loaded just fine.

We recommend you shut down the system and remove the connector from the pitch servo and meter between the CWS/DISC pin and the CAN bus pins while you push the CWS/DISC button to make sure that there is no continuity between these.

You might also carefully inspect the connectors and pins on both sides of this servo connection to make sure that all are properly seated. A backed off pin might explain the need to re-secure the connector as described.

Thanks,
Steve

Just wanted to follow up: I trimmed the end of the stick, and tested the CWS/DISC switch (this is an Infinity grip btw.) I did some fast morse sequences on the switch, and it worked perfectly: showed "open" when not pressed, "low" when pressed, and had no effect on network error rate when rapidly pressed. I did not find any evidence of a short between the CAN bus and CWS conductors, and the pins seem well seated in the pitch servo connector. So for now, everything is good.