Post by thread:Ask R/C PCM Standard !!!! sure

Hi clide, >I don't believe there is a standard - all the manufacturers have their >own encoding schemes. The servos are still driven with PWM signals, and >are more or less compatible, but the PCM receivers are not interchangable, >unlike the PWM receivers, which like the servos, are more or less >compatible between manufacturers. First, All the servo which accept positive pulse to be drive are compatibles. From all the manufacturer: futaba, lextronic, robbe, and so on= ... The main incompatibility is often the cable ! All the servo have the following input: - pulse width 1ms to 2ms to have a complete rotation (sometime 90=B0= , 120=B0 or 270=B0 it depend of the servo). The most of the transmitter allows= to adjust this width to increase or decrease the total deplacement. - SURE there is a PCM standard, what it's in the hard is a special code which identify the receiver. In many transmitter it's not possible to exchange this code, that's the reason why you cannot exchange a ROBBE PCM receiver and a FUTABA PCM receiver. =20 - It's quite easy for me to design a numerical way to send servo position to a receiver. But my purpose is not to create a new encoding sheme, but to be as far as compatible with other materiel. You know what I am talking about because you already download the first step of this project: RX-FM synthetised receiver. Regards, Philippe.

Hi Philippe, Clyde wrote: >> >> I don't believe there is a standard - all the manufacturers have >> their own encoding schemes. The servos are still driven with PWM >> signals, but the PCM receivers are not interchangable, then you replied: > > - SURE there is a PCM standard, what it's in the hard is a > special code which identify the receiver. In many transmitter it's > not possible to exchange this code, that's the reason why you cannot > exchange a ROBBE PCM receiver and a FUTABA PCM receiver. > > - It's quite easy for me to design a numerical way to send > servo position to a receiver. But my purpose is not to create a new > encoding scheme, but to be as far as compatible with other materiel. From a practical stand-point, I'd have to agree with Clyde that the PCM receivers are not interchangeable. And you may be right that they all use the same encoding -- but I've never seen any information on the PCM encoding or signature that causes the receiver to belive it is receiving a valid signal. The PCM transmitters & receivers are the top of the line and command premium prices. I believe each manufacturer considers their encoding proprietary. You can probably reverse engineer it. But I doubt that any manufacturer would guarantee not to change their PCM protocol, or even notify you of the change, unless you were buying huge volumes. On the other hand, you might get lucky and find such a standard. If you do, I'd be very interested in having a copy. Lee Jones ------------------------------------------------------------------- Jones Computer Communications spam_OUTleeTakeThisOuTfrumble.claremont.edu 509 Black Hills Dr, Claremont, CA 91711 voice: 909-621-9008 -------------------------------------------------------------------

{Quote hidden}>Hi Philippe, > >Clyde wrote: >>> >>> I don't believe there is a standard - all the manufacturers have >>> their own encoding schemes. The servos are still driven with PWM >>> signals, but the PCM receivers are not interchangable, > >then you replied: >> >> - SURE there is a PCM standard, what it's in the hard is a >> special code which identify the receiver. In many transmitter it's >> not possible to exchange this code, that's the reason why you cannot >> exchange a ROBBE PCM receiver and a FUTABA PCM receiver. >> >> - It's quite easy for me to design a numerical way to send >> servo position to a receiver. But my purpose is not to create a new >> encoding scheme, but to be as far as compatible with other materiel. > >>From a practical stand-point, I'd have to agree with Clyde that the >PCM receivers are not interchangeable. And you may be right that they >all use the same encoding -- but I've never seen any information on >the PCM encoding or signature that causes the receiver to belive it >is receiving a valid signal. > >The PCM transmitters & receivers are the top of the line and command >premium prices. I believe each manufacturer considers their encoding >proprietary. You can probably reverse engineer it. But I doubt that >any manufacturer would guarantee not to change their PCM protocol, or >even notify you of the change, unless you were buying huge volumes. > >On the other hand, you might get lucky and find such a standard. If >you do, I'd be very interested in having a copy. > > Lee Jones > >------------------------------------------------------------------- >Jones Computer Communications .....leeKILLspam@spam@frumble.claremont.edu >509 Black Hills Dr, Claremont, CA 91711 voice: 909-621-9008 >------------------------------------------------------------------- > >