Regarding Goto Angular Position Command in DiSEqC 1.2

[mohanaprakash]

Hi

I am using SG2100 motor for dish movement, when i give the command E0 31 6E 01 40 it move properly to 20 deg East but when i give E0 31 6E FE C0 it not moving to 20 deg West.

If i give any command to move in west it is not moving, some time for that also it is moving in east direction.

So can some one tell me some Example DiSEqC message for moving my my dish in west direction.

 

[Machman]

You're using the wrong command set... those are for terrestrial antenna rotators. The correct commands are E0 31 6E D1 40 for 20°W and E0 31 6E E1 40 for 20°E. The last nibble is the fractional degree setting, which is in units of 1/16° (the DiSEqC spec explains this almost correctly, but leaves out some valid values such as 4h and Fh).

These commands aren't documented publicly (until now, I guess ). I found them by intuition alone. They are probably documented in the USALS spec, but I've never seen it so there may even more that I'm unaware of.

 

[mohanaprakash]

Hi

can you explain me what D and E means in first data byte.

I know that 1 means add 256 and F means minus 256

 

[Machman]

D means go west of zero, and E means go east of zero. I don't believe 0, 1, and F are applicable to this type of motor (again, DiSEqC positioner application notice section 3.10 only specifies commands for terrestrial positioners). I don't know why 0 worked to move east in that nibble for you but it's probably just an design error in the SG2100's command decoding. My PowerTech DG-240 doesn't respond at all to the commands you tried (the LEDs don't even flash).

 

[mohanaprakash]

Hi

Thanks for your reply

My motor moving only when the polarization is vertical, when the polarization is horizontal is not moving.

 

[mohanaprakash]

Hi

if i am using command byte as 0x68 (east) or 0x69 (west) means the motor is running only if the data byte is less than or equal 0x04.

if anyone knows the reason please inform me

 

[Machman]

My motor moving only when the polarization is vertical, when the polarization is horizontal is not moving.

Use a voltmeter to check whether the cable has ~18V when horizontal is set. I have seen receivers with a damaged regulator that would only put out the correct voltage on one polarity.

Also make sure you are waiting long enough after setting the LNB voltage before sending the command. I think the DiSEqC bus specification explains this. For testing, a delay of one second should be enough. I also like to send a single halt command after that delay to put the motor into a known state. Otherwise it may sometimes drop the first command sent to it.

if i am using command byte as 0x68 (east) or 0x69 (west) means the motor is running only if the data byte is less than or equal 0x04.

I think that's a safety feature so that the motor will turn for no more than four seconds at a time, in case the data byte is corrupted on the wire or the halt command is lost. For longer timeouts you resend the command shortly before the previous timeout expires, as many times as necessary.

Note: it is mandatory to send a halt command at the time when the final timeout is expected to expire, since some motors might not support the timeout function.
Whenever sending the halt command, send it, and then send it again after delaying a few milliseconds. I have had problems with my motor not receiving the halt command when it is sent too soon after a movement command, probably due to the inrush transient on the cable when the motor starts moving.

 

[mohanaprakash]

Hi

I am using 4x1 DiSEqC switch and SG2100 DiSEqC motor.

DiSEqC motor is conected in position two of DiSEqC switch.

When i gave E0 10 38 C4 and E0 31 6E E1 A0 continuously i can able to see the orange light (Which indicates command receiving) glowing but motor is not moving.

Same when i give E0 10 38 C0 and E0 31 6E E1 A0 the power to motor is cut off (Green LED is OFF) so i can able verify switch is working but the motor is not moving to command. If anyone is having input on this please reply me.

 

[Tron]

Your DiSEqC switch should be between the LNB and the motor, not between the motor and receiver.

LNB -> DiSEqC (or other) switch -> Motor -> Receiver

 

[mohanaprakash]

hi
My understanding on DiSEqC switch is we can connect 4 dish as input to a receiver, with each dish having a motor.

LNB->motor->Switch position 1 |
LNB->motor->Switch position 2 |In -> Receiver
LNB->motor->Switch position 3 |
LNB->motor->Switch position 4 |



Whether my understanding is correct.

 

[Tron]

Hooking up motors to a switch in that fashion can burn the switch out, since motors draw an excessive amount of current.