Connecting Your Telescope

This page contains instructions for connecting your telescope's serial (RS-232) port to SkyFi's serial port. To do this, you'll need a serial cable that connects your telescope's serial port to a standard PC serial port. Different telescopes require different serial cables, so contact your telescope's manufacturer to obtain the correct serial cable for your telescope.

Once you've obtained the correct serial cable for your telescope:

1. Connect your telescope serial cable to the RS-232 port on your telescope. On most telescopes, the RS-232 port is a modular ("telephone") jack. On some telescopes, the RS-232 port is located on the mount base; on others, the RS-232 port is located on the hand controller.

2. Connect the other end of your telescope's serial cable to the DB9 male connector on SkyFi's serial adapter. Insert the other end of the serial adapter into SkyFi's RJ-11 serial connector. Make sure the connector clicks into piace securely.

IMPORTANT: Do not connect SkyFi to the AUX port, handbox port, autoguider port, or any other port on your telescope (or its hand controller) than its RS-232 serial port. Doing so may damage SkyFi and/or your telescope hardware. Make sure you know where the RS-232 serial port on your telescope is located, and only connect SkyFi to that port.

You don't need to use the mini null-modem adapter supplied with SkyFi when connecting it to a telescope. This null-modem adapter is only needed when connecting SkyFi to a PC serial port for firmware updates. Click here for details.

You can attach SkyFi to your telescope's mount or tripod with the supplied strip of Velcro. Make sure SkyFi's serial adapter is not kinked, that there is a decent amount of slack in your telescope serial cable, and that all connectors are fastened securely.

Building Custom Serial Cables

Alternately, you can build a custom serial cable to connect your telescope to SkyFi, without using SkyFi's RJ-11-to-DB9M adapter.

Like SkyFi, most telescope serial ports also use 4- or 6-wire modular jacks. Unfortunately, telescope manufacturers have not standardized on a common serial port pinout. In other words, pin 1 on the serial jack for a Meade LX-200 may carry a different serial signal than pin 1 on the serial jack for a Celestron NexStar GPS.

If you can obtain the pinout diagram for your telescope's serial port, you can build a simple "telephone" cable to connect SkyFi's serial port directly to your telescope's. The following diagram shows the meaning of the pins on SkyFi's serial adapter cable:

Pinout diagram for SkyFi's RJ-11 to DB9-M serial adapter.

This diagram, combined with your telescope's serial pinout diagram, should allow you to construct a simple telephone-like cable for connecting SkyFi's serial port directly to your telescope's serial port. The following table lists the pinouts for SkyFi's serial adapter, and for several common telescope models. Note that some telescope serial ports use a 6-pin RJ-11 connector similar to SkyFi's; while others use the smaller 4-pin modular "handset" connector. Check your telescope manual for details, and expect some trial and error.

Manufacturer:	Carina	Generic	Carina	Celestron	Orion	SkyWatcher	Meade	Meade	StellarCAT	Wildcard	Losmandy
Model:	SkyFi	Phone Cord	SkyFi	NexStar, CGE, CPC, SLT, SE	Sirius, Atlas	SynScan	ETX, LX-90, LXD55/75	LX-200 Classic, GPS	ServoCAT	Argo Navis	Gemini
Connector:	6-pin RJ-11	Conductor Color	DB-9 Male	4-pin modular	6-pin RJ-11	6-pin RJ-11	4-pin modular	6-pin RJ-11	6-pin RJ-11	6-pin RJ-11	4-pin modular
	2	Black	3	4	5	5	4	5	2	3	3
	3	Red		3	4	4	2	3	4	5	1
	4	Green	5	2	3	3	1	2	5	4	2
	5	Yellow	2	1	2	2	3	4	3	2	4

Pins are numbered 1 to 6 from left to right when facing the connector with the pins down and plastic clip up, as pictured above. Note that the outermost pins (1 and 6) are not used on any 6-pin RJ-11 connector!

Please note that Carina Software does not provide support for building custom serial cables.

SkyFi's Serial Hardware

SkyFi's serial port supports baud rates from 300 to 230400 bits per second, and includes the transmit data (TD), recieve data (RD), and ground (GND) signals. SkyFi's serial port does not support hardware flow control. However, very few serial devices actually require hardware flow control, so this should not be a problem for most applications.

The pins on the DB9 male end of SkyFi's adapter correspond to exactly the same pins on a real PC serial port. In other words, the DB9 male connector on SkyFi's serial adapter works exactly the same way as a PC serial port.

To connect SkyFi's serial port to a real PC serial port, insert a null-modem adapter between the DB9 connector on SkyFi's adapter cable, and the DB9 connector on the PC. A female-female mini null-modem adapter is included with SkyFi for exactly this purpose. You'll need to use this adapter when connecting SkyFi to a PC serial port for firmware updates.

Configuring SkyFi's Serial Settings

You can use a web browser to configure SkyFi's serial port settings. To do this, first join SkyFi's wireless network, then browse to http://10.0.0.1/, or to whatever IP address you have assigned to SkyFi.

The baud rate, parity, number of data bits, and number of stop bits, can all be selected from the dropdown menus at the bottom of SkyFi's configuration web page. You can also select the TCP port on which SkyFi will transmit data from its serial port to the wireless TCP/IP network, and vice-versa. By default, that TCP port is 4030, but you can use any other port from 1024 to 65535. Only one network device can be connected to this TCP port at a time.

When you are finished, click the "Save Changes" button. Note that this will interrupt any serial communication already in progress.

Programmers writing custom applications can control SkyFi's serial settings using standard HTTP requests with simple CGI parameters. The HTTP requests should be sent to SkyFi's IP address on port 80. The CGI command is /setserial, and the CGI parameters are as follows:

Serial Setting:	Baud Rate (bits per sec)	Parity Setting (none, even, or odd)	Data Bits	Stop Bits	TCP Port
CGI Parameter:	baud	parity	data	stop	tcp_port
Possible Values:	300 1200 2400 9600 19200 38400 57600 115200 230400	N E O	5 6 7 8	1 2	1024 ... 65535

The HTTP response code will be 204 (no content) if the request succeeded, or 500 (server error) if the request failed. If the parameters are incorrect, SkyFi will not change the serial settings. Here is an example:

http://10.0.0.1:80/setserial?baud=19200&parity=E&data=5&stop=2&tcp_port=5678

This will set SkyFi's serial port to use 19200 baud, even parity, 5 data bits, and 2 stop bits. Serial data will be relayed to and from the wireless network on TCP port 5678.