SynScan Hand controller pinouts

[ribuck]

Hi all,

I was wondering if anyone knows what voltages the SynScan controller RJ11 pin outs use.

In particular i'm interested in pins 2 & 5 used for data recieve and transmit.

Rich.

[steppenwolf]

This doesn't exactly answer your direct question but the following may help:-

On the DB9 End:-

Pin 5 is ground potential

Pins 9 & 6 are at TTL levels (5v)

Pin 1 is 12v

If you trace these back to the RJ11 end with a continuity tester, you will be able to determine the pins on that plug.

[ribuck]

Hi Steppenwolf,

What about pins 2 & 3, do you know what they are at, as they are the ones i'm interested in, as they control the Tx & Rx

Rich.

[steppenwolf]

They will be at 5v TTL level as well

[ribuck]

steve are you 100% sure as i'm sure RS232 operates at a higer voltage than TTL, that's why you normally need a RS232 to TTL convertor. I'm just workingon an electornics project with an Arduino board and dont want to fry it.

[steppenwolf]

I am basing this on the following:-

.... to control an EQ6 Mount DIRECTLY from a PC, you require a converter that converts RS232 to TTL levels, therefore, as the hand-controller connects directly to the mount in place of said 'converter' it is fair to assume that the control signals from the hand-controller are also TTL. Not knowing exactly what you have in mind, this is educated supposition but the following link may assist:-

Circuit Diagram Here

[ribuck]

Thanks Steve,

Looking at the diagram it's using the max232 chip to convert to TTL, i think i'll get a Max232 just to be better safe than sorry, as i dont want the mount controller to blow.

Rich.

[Beyond_Vision]

What output do you intend using on the Arduino Board if it has TTL level digital I/O output all you would need is a non-inverting TTL buffer chip to protect the board.

Regards

Kevin

[ribuck]

Hi Kevin,

all i'm trying to do is read the scopes position using the transmit pin of the hand controller, and pass that to the Arduino board.

From that the processor will do some maths and convert it to Azimuth to then drive a dc motor driver using a driver board.

So the only output i have it the output to the Dc motor driver which is 5v.

Regards,

rich.

[Beyond_Vision]

If the Arduino has 5V TTL compatible input line then all you need is a non-inverting TTL buffer chip to act as protection. In theory you could directly connect the mounts TTL Tx output to a TTL digital input line of your processor card. There is no need to use a RS232 transciever.

Regards

Kevin

[ribuck]

Hi kevin, i put a volt meter across the pins and they are reading 6.85 volts, so this will be too high for the Arduino board.

[Beyond_Vision]

Seems a bit odd it should be 5V logic. The mount connection is certainly not RS232 levels which will be +/-5V or higher. There have been a few mounts damaged by people trying to connect a PC's RS232 output directly to the DB9 connector. I would try putting a resistor of 10Kohms across the TX line output whilst you measure the signal level. Ideally a oscilloscope would be the best thing to measure it with since if data is being transmitted the signal will be toggling.

Regards

Kevin

[Lord F]

I'm not sure if this will help, but i measured the voltage on my handset at about 6.9v too.

[ribuck]

Thanks Lord F. that's a big help, as it confirms that my measurements are correct and that the voltage would be too much for the TTL of the Arduino.

[steppenwolf]

This is very interesting because the EQDIR adapter is a TTL device and has it's own 5v regulator on board but if you have an external device that is voltage sensitive then you will indeed need to tread with care. Presumably there is a pull-up resistor in play here so the voltage is being measured 'off load' but I have no idea how significant that is and whether the on load voltage would be more compatible?

[ribuck]

Hi Steve,

The device i'm building is basically a dome automation system, which will be permanently attached, to my mount to get readings, so when the mount first powers up and the volathe is over 5v this could cause some serious damage.

i've ordered a RS232 to TTL, so i'll just add that to my design to sort out any power issues.

Rich.

[Beyond_Vision]

Whatever you do, do not connect the RS232 connections of the chip to the mount as you will damage it.

[ribuck]

God i'm getting really confused now, i dont understand the difference between connecting the Serial port of my pc which reads data from the hand controller and connecting a serial port connection from an Arduino to the hand ocntroller to read the data in the exact same way the pc does ?

Can you explainhow this differs in laymans terms ?

[Beyond_Vision]

The connection between the PC and the handset is RS232 with a TX, RX and 0v connection the RX,TX lines voltages can swing between greater than +5V and -5V with respect to 0V. The larger connection from the handset to the mounts DB9 connector is a TTL serial connection which consists of RX, Tx and 0v connections. The RX and TX lines will toggle between 0 and 5V never negative. If you directly connect a PC RS232 port or any other RS232 device to the mounts DB9 connector you will damage the mount.

You could use a serial RS232 input on your Arduino board and use a RS232 to TTL convertor chip (MAX232). You would have to connect the TTL side of the chip to the mount and the RS232 transmit output of the chip to the Arduinos RS232 receive input. The other method would be to use a port input on the Arduino and a non-inverting buffer chip to act as protection. This could be a simple 7400 series logic device or similar. If the input gets overvolted in any way it's only a cheap chip to replace and not the arduino.

[ribuck]

Ok i guess this is where the ocnfusion is coming from, as i posted earlier that i had purchased a Rs232 to TTL (Max232) and was planning to use that. not sure if you noticed that part of the post.

Here's basically how i understand the way it will be wired. I'm assuming this will be ok ?

[Beyond_Vision]

Sorry I was thinking you were trying to connect to the mount not the handset right hand RJ11.

The Synscan RJ11 connection is RS232. I presume your arduino board has a serial TTL input ? If so the MAX232 chips TTL output should be connected to it and the RS232 input should be connected to the handset.

Regards

Kevin

[ribuck]

Thanks Kevin, Yeah it's just the handset that i'm planning to use, and the Arduino board supports both analog and digital inputs, and had loads of pins, where you can define via programming if they are to be used as input or output, and there's also 2 dedicated pins for Rx/Tx as well, so i could use any of them really.

The Arduino boards are amazing for this type of thing.

Rich.