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VPX-Pro question

Don

Don

Well Known Member
I've powered up my VPX-Pro, updated the firmware, and installed the config file based on my work planning sheet. All of my switches are installed and I'm starting to test out circuits. I supposed I cheated just a little and installed both an Hx as my primary EFIS and an HS as my secondary and checked them out together.

The manual says to wire the primary EFIS to J12-9 and my worksheet had me wire the power to the HS from J10-3. On both devices I tied the power to the Master Avionics Switch. When I flipped the master switch to on, the Hx powered up (not supposed to power up until the Master Avionics Switch comes on). The HS performed exactly as directed - it didn't come on when the Master switch was powered on and it did come on when I flipped the Master Avionics Switch.

I'm pondering if J12-9 might be an "always on" power source. If so, do I need to use it for the primary EFIS? I really don't care to have the EFIS on until after the engine start. I keep thinking I've done something stupid and I keep missing it but I've checked the pins - the EFIS is in J12-9, I've checked and rechecked the switch wires and they're right (as shown by the HS EFIS working properly). There just isn't much I could screw up?but the Hx comes on too when the Master switch is turned on.

Have others used J12-9 for power to their primary EFIS and successfully programmed it to power on with your Master Avionics switch?
 
The power output for the EFIS that is always hot when the master is on must go to the EFIS that is connected to and controlling/displaying the VP-X.

This is the way it is designed to work.

For my G3X system I made sure to connect the VP-X to the MFD as that is what I wanted on during start for the EMS functions. The PFD1 & 2 don't get power from the VP-X until the avionics switch is turned on.

If you just can't stand for the primary EFIS to be on, one workaround might be to waste the Primary EFIS pin and hook both screens up to pins that are not marked as the primary EFIS. You may have to experiment with this to see if it will let you do that in the configurator.
 
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The logic for that pin always on is that you want your engine gauges visible to monitor that various sensors at engine start.
 
Don said:
I've powered up my VPX-Pro, updated the firmware, and installed the config file based on my work planning sheet. All of my switches are installed and I'm starting to test out circuits. I supposed I cheated just a little and installed both an Hx as my primary EFIS and an HS as my secondary and checked them out together.

The manual says to wire the primary EFIS to J12-9 and my worksheet had me wire the power to the HS from J10-3. On both devices I tied the power to the Master Avionics Switch. When I flipped the master switch to on, the Hx powered up (not supposed to power up until the Master Avionics Switch comes on). The HS performed exactly as directed - it didn't come on when the Master switch was powered on and it did come on when I flipped the Master Avionics Switch.

I'm pondering if J12-9 might be an "always on" power source. If so, do I need to use it for the primary EFIS? I really don't care to have the EFIS on until after the engine start. I keep thinking I've done something stupid and I keep missing it but I've checked the pins - the EFIS is in J12-9, I've checked and rechecked the switch wires and they're right (as shown by the HS EFIS working properly). There just isn't much I could screw up?but the Hx comes on too when the Master switch is turned on.

Have others used J12-9 for power to their primary EFIS and successfully programmed it to power on with your Master Avionics switch?
Click to expand...
Check page 31 of the install manual. J12-9 is always hot once the master switch is turned on, so the primary EFIS can display VPX faults if any.
 
Mark Dickens said:
Check page 31 of the install manual. J12-9 is always hot once the master switch is turned on, so the primary EFIS can display VP-X faults if any.
Click to expand...

Mark, I'm guessing we're using different versions of the manual. My page 31 covers Pitch and Roll Trim wiring. It is good to know J12-9 is always hot once the master switch is turned on because that's what its doing even though I reconfigured it differently.

All, My inclination is have my EIS on when the Master Switch comes on. That way I'll know my oil temp before starting and I can watch oil pressure come up (or not) after starting the engine. That seems a lot more important to me initially than knowing any VP-X faults.

After starting the engine, I'd want the EFIS's to come on with the Master Avionics switch and then I can determine what the status of everything else is. Perhaps I'm missing something but that what I'm thinking now - and if I am missing something, I'm up for an education.

Does anyone see a problem if I go this direction and don't use J12-9 for either EFIS (I might use it for the EIS)? My page 28 is pretty emphatic that the EFIS that connects to the VP-X via the serial line "must be wired to the J12-9." I just don't like to have an EFIS on when I'm starting the engine…maybe I'm old fashioned but I worry about voltage spikes.
 
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Depending on your plane, there are many other parameters that are important for engine start. For me, I need my EFIS as the following details are needed during start.

Fuel Pressure and Fuel Flow - needed for Priming
Battery Voltage - if there is a prolonged start or a failure to turn over
Oil Temp/Pressure during crank
RPM after cranking

So if your EFIS can handle it, why not have the info you will need during start rather than do it "in the dark"?
 
CharlieWaffles said:
Depending on your plane, there are many other parameters that are important for engine start. For me, I need my EFIS as the following details are needed during start.

Fuel Pressure and Fuel Flow - needed for Priming
Battery Voltage - if there is a prolonged start or a failure to turn over
Oil Temp/Pressure during crank
RPM after cranking

So if your EFIS can handle it, why not have the info you will need during start rather than do it "in the dark"?
Click to expand...

Mark, it's not that I want to do it "in the dark" but rather on the EIS rather than the EFIS. It seems to me it would be gentler on the EFIS. On the 9A I'm flying now, the Dynon D100 stays off until after the engine start and I get the information on a VM 1000C. My understanding is starting an engine can result in spikes. While I'm not interested in replacing anything prematurely, I'd sure rather replace an EIS rather than an Hx - the difference is many thousands of dollars. I guess I'm curious why you want to do it the EFIS?
 
The "spikes" were issues with older EFIS systems, but just about anything made in the last few years handle the lows and highs in the electrical system without any issues. So for me, all of the engine information is on the EFIS.
 
For my panel I start with the critical systems also connected to the backup battery bus and this helps prevent reboots during starting.

Will your EFIS have backup power?
 
Don, are you saying your panel has 1 EIS and 2 EFIS units?

If so, hen ad long as your EIS givens you the data you need to comfortable and safely start your engine, your proposal of having the EIS on via J12-9 and your EFISs tied to the Avionics seems sound. I would suggest you have backup power for one EFIS.

My panel has a combined EMS/EFIS on master power with a backup source. This prevents a voltage drop during engine start. My flight EFIS comes on with the Avionics.
 
One thing I'd check out is whether the VP-X will error out if it isn't able to connect via serial port to the EFIS upon start up...VP is pretty emphatic in the manual about this putting it in bold and underlining this...just a thought.
 
Nope, the VP-X can run without its EFIS. You only have control of whatever is connected to a switch configuration and you are blind so to speak but it will run as programmed even without the EFIS.

Personally I would connect it as designed as most if not all of the modern EFIS system makers have said that being powered on during start is not a problem. Add in that most people have the backup power inputs hot during start also minimizes the risk of a reboot. Brownouts during start are hard on any electronics. Having the backup inputs hot during start eliminates this issue all together. Spikes during startup came from long ago when the older avionics were easily damaged by voltages outside a very tight tolerance. Units these days have totally different power supply circuitry and can tolerate much wider range of voltages.
 
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Glen, I have EFIS 1, EFIS 2 and an EIS.

Mark, The manual is emphatic, which is why I'm asking.

Brantel, I am leaning toward adding a battery back up for at least one EFIS and maybe a com. Also, your last post answered the question I was trying to ask. I'd lose control over anything not switched - that explains why I want to stick with the plan VP intended?which is how its connected right now.

Thanks gentlemen, I understand.
 
I do wish that pin was programmable for always hot or not. I have battery backup which I intended to power my efis during startup. While it certainly works fine as designed, I would prefer it let me decide how I want it to function.
 
ColoRv said:
I do wish that pin was programmable for always hot or not. I have battery backup which I intended to power my efis during startup. While it certainly works fine as designed, I would prefer it let me decide how I want it to function.
Click to expand...

Just put a switch on it.
 
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