jtholley03

My Feedback: (4)

For some reason I can't finer this one out. With servo positioning I am using the outer hole in a servo arm for linearity. I have to limit the servo to about 52% travel. My stick is dead after about the same amount. How do I restore 100% stick movement while keeping my 52% limit on the servo.

HarryC

My Feedback: (1)

Do you mean the servo stops moving at about half stick? The most common cause of that is the servo hitting its mechanical end stop because you have adjusted the control or servo centre to way off normal. If you have autotrim enabled you could have cumulatievly added trim until without realising it the servo is way off centre and near its end stop. Another possibility is you have multi point curves and you have made a S shaped curve so that all points beyond mid stick are the same value.

Check that menu 4 Tx mode is PPM9 and neutral pnt = other. In menu 1 make sure that the control centre is at 0 and travels are at 100% both ways, trim centre is at or close to 0. Ensure autotrim is off. Then check servo centre and limit for 0 and 100% respectively, then travel/curve for a straight line. If you need 52% travel, then adjust it in this menu, not in the control travels menu.

Harry

jtholley03

My Feedback: (4)

Everything is as you said. No auto trim, limitation is done in servo centre+Lim. I have it set to 47-52 depending on servo so no binding occurs. No multi point curves. Controls are 100% with 0 centre.

So now what?

brancolitw

BTW, HarryC,

When should I set:

Tx mode = PPM9/12?
What to set if using (1)Mpx IPD 12, (2)Mpx 9ch (3)Futaba 7/8 ch receiver?

Neutral point = other/MPX?
Does it refer to MPX recevier or servo?

Thanks.

HarryC

My Feedback: (1)

JTHOLLEY -

It is either a faulty servo or you have got some odd programming parameter dialled in. Try a clean memory to operate that servo to ensure that the servo does respond as usual. Otherwise, perhaps you have another control mixed in to that servo which is greatly offsetting the centre and causing it to hit the end stop. Does it stop at half stick travel in both directions, or just in one direction? Is the servo assigned directly to one control, or to a mixer?

Harry

HarryC

My Feedback: (1)

Brancolitw - The TR.MODE must be set as per the receiver. If you use an Mpx 12 channel Rx you must use the 12 channel Tx mode even if you only use a few channels. You must not use the 12 channel Tx mode unless you are using an Mpx 12 ch Rx. The reason is that to keep refresh rates high with 12channels, the Tx compresses the data and the Rx expands it again. If you mismatch the Tr mode and Rx, they will work together but centres and travels will be wrong. I suspect you will have to manually adjust servo centres to minus 9% to match the existing centre of a uni servo since I think servo type parameter is not available in 12 ch mode and it assumes you are using Mpx servos.

The servo type is set for the servo plug type, and is not related to the Rx used. The Mpx centre is used only with Mpx servos that are fitted with the Mpx brand specific plugs. Any other brand of servo, or an Mpx servo that is fitted with JR plugs, should be set to the "other" type. Note that this only adjusts the centre to uni timing, it still leaves the travel times at Mpx standard. To make the servo match the travel it would get from a JR Tx set to 100% you adjust the Mpx travel to 73%, to match a Futaba Tx set to 100% set the Mpx travel to 78%.

Harry

jtholley03

My Feedback: (4)

The stick position/servo stops the same - about halfway each direction. I think I will start on a new memory and reprogram. I don't have any mixers applied. It is just a simple setup.

I think if I just resart from scratch I will figure it out.

Nother ?
The 7,9,12 receivers. Do they all have the same high resolution. Is it just the 12 that is compressed? The reason I ask is they advertise the 12 as high resolution on all channels and don't say diddly about the 7 and 9. I know the Tx has to be set to the proper parameter and that makes sense since you say the 12 uses a different algorythm. I just want to make sure if I get a 9 instead of 12 for a JOKER heli I don't give up any resolution.

Thx for input, I will post when I figure out *** I have done.

HarryC

My Feedback: (1)

JT, check the LIMIT parameter, you may have turned that down from the default 100% and that would cause the symptoms you are getting.

All Rx and all Tx modes are full resolution, equal priority, fully proportional channels.

Harry

Tobias Schlegl

Hi Harry!
Yes, JT mentioned two times that he adjusted the LIMIT value and not the ATV. Maybe it's neccesary to explain the differences here.

Tobi

HarryC

My Feedback: (1)

Oh yes! JT, the servo travel adjust is in the curve screen. The LIMIT parameter is designed to provide a maximum travel when servos receive a mixer signal which may add up cumulatively to more than the servo can handle or would make a ridiculous control surface deflection. It should not be used to adjust travel response to any one control. The LIMIT parameter acts as a max travel % number that can be transmitted. If you set it to 52% then the servo will still contain a 100% response curve to the stick, but if the stick goes beyond 52%, the servo will simply stop moving at 52%.

Leave the LIMIT at the default 100%, there are few times that you would need to adjust it. I only alter it, up to 109%, when I am using the max possible throws on a 3D model. I turn the servo travel up to 109%, but if I leave the LIMIT at 100% it will stop at that so I have to alter LIMIT to 109% as well.

Harry

brancolitw

How about tx mode PPM7 and PPM9?
What is their difference?

Any tricks done on the Mpx plug? I suspect the wiring of a uni plug and mpx plug are the same, just plug shape difference!!! How can they give different centre and limit travel?

HarryC

My Feedback: (1)

PPM9 is the standard mode to use for a PPM Rx no matter how many channels the Rx has. PPM7 is provided just to give backwards compatibility with an old Mpx Rx that you are very unlikely to have.

The difference in plugs is that they are a “label” for the timing that is designed into the servo. Mpx servo timing is centre 1.6ms +- 0.55ms. That is what your Tx sends in Mpx mode, and the servos are designed to work on that. Realising that they could sell servos to non-Mpx users, they also make their servos with uni plugs and uni timing of centre 1.5ms +- 0.4ms. So the plug tells you what the servo’s electronics are timed for. Taking an Mpx plug servo and replacing the plug with a uni plug would still mean the servo operated to Mpx rather than uni timing.

Maybe you don't get a choice where you live, I know they don't in the USA, but in Europe we can buy their servos and Rx with either Mpx or uni plugs and have to specify which when we order.

Harry

rorywquin

Harry

I believe that the wire insulation colour also tells you the information- red, brown, orange = uni. Red, black, yellow = Multiplex!

jtholley03

My Feedback: (4)

Travel 1/-109, travel 2/0, travel 3/109.

Limit -47. Do i have these backwards cuasing the TX stick to reach full travel @ 50% stick movement?

Thx

HarryC

My Feedback: (1)

The servo LIMIT function should be at 100%. You do not use it to adjust travel.

Harry