RadioMaster Tx16 with JR module issue

[Falco]

Currently I am using an XPS JR module in a RadioMaster Tx16s with 16+ nano receivers.  Before this I was using the Futaba module in my 9c radio.  I have used the RM setup for the last three seasons. Last season I crashed my funjet due to loose of control.  Unable to determine the cause I replaced the nano Rx and gyro and moved on.  I had no issues till about two weeks ago, I tried to fly my funjet on a hot ~85-degree day and during my preflight I noticed the servos movement was choppy and lagged the stick movement.  I had several flights before this on other models.  I assumed it was either the nano receiver or possibly the gyro in the plane.  I could not reproduce the issue on the bench, so again I replaced both the rx and gyro (installed another nano rx) and had no issues for several flights since.   

This past weekend I was out (again a hot 85 degree day) and tried to fly 71” Slick about mid day after 3 previous flights.  I experienced the same laggy choppy servo movements.  This time I immediately switched to the funjet and had the same issue making me think its an issue with the XPS module.  I wish I had then immediately switched to my small heli with a Spektrum rx (to rule out the radio) but this didn’t occur to me.  I later (same day) flew the heli for several flights and had no issue.  Both sessions were hot sunny days and I sometimes leave the radio on while changing packs.   Till I resolve this issue I don’t feel confident in using my XPS equipment.  Do these symptoms sound familiar?  Could this be a heat issue or just a failing module?  I see the JR modules are out of stock.  What are my options?  Thanks for any assistance.

[XPS]

If you check our local temperature you will find it around 120 degrees today. We developed the XtremeLink system (17 years ago now) in these conditions, so heat should never be a factor for our products. It's more likely that the RadioMaster transmitter is affected by heat. Did you try the XPS module again either before or after you flew the heli later in the day?

We have never had a report of a problem with heat with our system, because that was actually a very large focus at one point in the industry when Futaba did have this problem with one of their large receivers used in giant scale 3D aircraft.

Of course, anything is possible. But, one thing that needs to be mentioned is that you can cause the choppy servo movement with the Nano (or other receiver options) if you do not bind the receiver with the exact number of channels being used. For example, if you bound the Nano with 6 channels assigned and you found out later that you really only needed 5 channels or you needed 7 channels, and made the change necessary without rebinding afterwards, you can experience the choppy control because the wrong frame rate data and number of channels is being used. Typically, this is immediately noticeable but not always. The Nano does a good job of trying to fix issues like this in real time. This is something that you should probably check.

[rlocke]

try this put the transmitter in a cardboard box with a trouble light. wait for a while and test an aircraft. if it acts as you described it is the transmitter. this happened to me. i had it fixed and no problems since. ron

If you check our local temperature you will find it around 120 degrees today.  We developed the XtremeLink system (17 years ago now) in these conditions, so heat should never be a factor for our products.  It's more likely that the RadioMaster transmitter is affected by heat.  Did you try the XPS module again either before or after you flew the heli later in the day?

We have never had a report of a problem with heat with our system, because that was actually a very large focus at one point in the industry when Futaba did have this problem with one of their large receivers used in giant scale 3D aircraft.

Of course, anything is possible. But, one thing that needs to be mentioned is that you can cause the choppy servo movement with the Nano (or other receiver options) if you do not bind the receiver with the exact number of channels being used.  For example, if you bound the Nano with 6 channels assigned and you found out later that you really only needed 5 channels or you needed 7 channels, and made the change necessary without rebinding afterwards, you can experience the choppy control because the wrong frame rate data and number of channels is being used.  Typically, this is immediately noticeable but not always.  The Nano does a good job of trying to fix issues like this in real time.  This is something that you should probably check.

[Falco]

Quote: It's more likely that the RadioMaster transmitter is affected by heat.  Did you try the XPS module again either before or after you flew the heli later in the day?

I did not try the XPS module later in the day while at the field.  I did try several times at home on the bench and was unable to reproduce the issue.  I also heated the module to +100 degree outside the radio using an extension to the radio and was unable to reproduce the issue.  I wish when it happed after switching to a second XPS receiver I had tried a non XPS receiver to rule out the radio (this may not have been conclusive).  Perhaps the issue is with both the RM and the module.  Never had a hiccup with my 9c and futaba module.

Quote: you can cause the choppy servo movement with the Nano (or other receiver options) if you do not bind the receiver with the exact number of channels being used.  For example, if you bound the Nano with 6 channels assigned and you found out later that you really only needed 5 channels or you needed 7 channels, and made the change necessary without rebinding afterwards, you can experience the choppy control because the wrong frame rate data and number of channels is being used.  Typically, this is immediately noticeable but not always.  

I did experience this when I first got the Radiomaster.  I was told (by XPS) to move the module mode from PPM to XJT.  This seemed to resolve the issue.  Attached is an image of the settings I'm currently using on the RadioMaster and the JR XPS module.  Normally there is no apparent issue( for hundreds of flights).  When the issue presents during preflight, it is obvious and the aircraft would be unflyable.  I could switch the mode to XJT D8 and reduce the channel number.  I'm not sure if that would make a difference. Unfortunately the issue is not normally present and therefore difficult to know when it is resolved.  I would like to be able to figure this out so I don't have to give up my many Nano receivers.  Thanks for any assistance.

   

[Falco]

This is the thread about putting the Radio\module in XJT D16 mode.

https://www.xtremepowersystems.net/forum...php?tid=25

[XPS]

XJT mode is required if you need more than 8 channels. It's also a faster protocol in general, so it should be used when possible.

The issue with XJT mode though is that you can turn on/off the channels that are used. Once you have bound the receiver you can't turn on/off channels at that point (unless you rebind again after doing so).

[Falco]

If 16 channels are not needed is there and benefit to use D8 in the XJT mode?  As far as my issue I don't believe the is a problem with either the radio or the module.  Perhaps it has something to do with the radio\module and EdgeTx?

[Falco]

Perhaps the issue I have experienced would be resolved by going back to PPM mode on the module.  I never saw it on my Futaba 9C with the XPS module.  My 9C was used in PPM mode.

[flyingw]

If 16 channels are not needed is there and benefit to use D8 in the XJT mode?  As far as my issue I don't believe the is a problem with either the radio or the module.  Perhaps it has something to do with the radio\module and EdgeTx?

There is no benefit to setting the transmitter's output to D8 (8 channel) mode.  The XPS transmitter module sends groups of 16 channels at a time whether OpenTx or EdgeTx send 8 or 16.

I've successfully used the XPS-J1 transmitter module in XJT-16 mode in both a Taranis and a Jumper T12 for years.

[Falco]

I'm not sure what my issue is and its only happened a few times since I got my RadioMaster TX16s back in April of 22'.  I never had a problem with my Futaba 9C in over 10 years with an XPS module in PPM mode.  Today I switched my JR module from XJT back to PPM mode and rebound most of my nano receivers.  XJT mode should not be a problem but this is the only thing I can think to change.  Hopefully this will resolve my issue, if not I will post back.  One more episode and I will move on to ELRS for most of my models.