Please help. I have written a program using the servo library to move a servo to jig my fishing rod. It works great with a Tower Pro MG995 servo. I was sent an upgraded version a Tower Pro MG996R. . Changing nothing and going from the MG 995 to the MG 996R, the Mg 996R just spins in a full circle. it does not jig back and forth like the mg995. I have a separate power supply ( 6 volts) running the servo. I have it grounded to the board. Again the MG 995 works and the MG 996R does not. Can someone please help? Thank you
Hi,
The "R" means this is a "Robot" servo and it rotates constantly, with its speed controlled by the usual signals, but something like 90 degrees is Stop, other values run in other directions.
UPDATE: SEE BELOW! So you MAY have a DIFFERENT Type servo with the R.
Despite what Terry says MG996R is simply the designation of the standard 180 degree servo which replaces the MG995. At least the 3 MG996Rs I have are all standard servos.
But it does have a continuous rotation version (confusing called the 360 degree version). So if you mean that the MG996R spins more than 360 degrees then it does sound like you have been given a continuous rotation servo and not a standard servo.
Or, less likely, it could be a power supply problem. From what I remember the 996R uses higher current than the old 995.
Of course the code you haven't shown us could still be at fault. Try it with the Sweep example code.
Steve
Hi,
Wow.. there is some confusion between manufacturers, labels and ME/Us...
I have MG995 and MG995R here and those use R to mean Robot or continuous. BUT the manufacturer NOW seems to have used "R" as "Revised".. I ASSumed the MG996 would be the same.
Tower Pro http://www.towerpro.com.tw/product/mg996r/
Says "MG996R is an upgraded version of MG995 servo.
The new PCB and IC control system which makes it far more accurate.
Its internal gearing and motor are also upgraded to improve dead bandwidth and centering"
So "Despite what Terry says" 
the labelling is in question. If your servo is a Chinese clone of the Japanese MG996 then maybe that's the source of confusion.
Please let us know what you find out so we (I) can be a little less confused.
Yes it's a pain. From what I can see there's no visible difference between the 180 degree MG996R and the 360 degree (continuous) version. You have to connect 'em up and see what they do. Not very helpful.
And as you say there are clones out there that might do anything!
Steve
What would you like to see? The program uses the servo Library. I wrote it and I am running the Tower Pro MG995. I am making in move basically from 0 degrees to 90 degrees and back to 0 with different delays. It has worked for me for years. I have changed nothing but to connect the Tower Pro MG966R. All it does is turn continuously in a circle not back and forth.It is a separate 6 volt power supply and the ground is grounded correctly.
And does it also turn continuously one way when you try the Sweep program? Then you have either the wrong version of the MG996R or a bad one. Send it back and get a standard 180 degree version instead.
Steve
I did some research on the servo. It comes in both 180 and 360 . If I have the 360 would I be able to move it back and forth like I can the MG 995 or would I need the 180 degree servo. I am talking about the MG996R.
As I said earlier (several times) the "360" version is a continuous rotation servo, no control over position. It just does what you are describing yours as doing. It's not really a "servo" at all. It's a geared motor with its own controller.
The 180 degree servo is the one which is equivalent to an MG995 with full positional control.
Steve
Steve forgive me for being so ignorant. This makes perfect sense. Not to throw a wrench in the discussion but the MG 995 comes both 180 and 360. So what you are saying is that I must have the MG995 180. That is why I can control it. If I had the MG996R 180 I also should be able to control that. In the past I have ordered the MG 995 FROM MULTIPLE SOURCES and they always have worked. I have never specified a 180 or a 360. That is over a three year span. I must have been lucky? I need to look into how to be able to order a 180 version of the mg995 and the mg996r. I appreciate this input because I have been resourcing and asking multiple sources to solve this. Any other input is great appreciated. Thank you
Now I am an idiot. Sure enough the purchase I made says 360 not 180. I am stupid! Now I do need help. If I were to find the SWEEP program, do you think I can control the 360 servo?
No, Sweep won't help. The 360 servo has no positional control. Changing the write() value just changes the speed and/direction of movement. There is no practical way to send it to a position and then later send it back to the original position like you can with a normal servo.
Steve
Steve I hope you read this. I have learned a great deal here. I wish to thank you for the help. It is frustrating to say the least when you know just enough to be dangerous. I appreciate the help. Thank you. Unfortunately for me I ordered and received 20 of the 360 servos that I can not use.
Admit your error to the seller and ask for an exchange.