Summary of our setup
The synscan HEQ5 mount can be controlled through the handset, but the serial protocol supported by the mount can also be used to interface directly to a computer.
The main connection is an 8 pin RJ45 connector with pinouts as follows ( and colours based on standard ethernet cable (B version which is the only one I ever see in practice).
- pin 1 and 4 ground (orange/white and blue)
- pin 5 tx (5v rs232) (blue/white) (connect to rx on the other side)
- pin 6 rx (5v) (green) ( connect to tx on the other side)
- pin 8 12v output (brown)
A note about voltage. There are various different places on the web which say different things about the voltages used by the mount. All I can say is that with my own adapter which is switchable between 3.3 and 5v it worked reliably at 5v but not at 3.3v
After trying various different approaches to the interface, we eventually built a cable which connects an RJ45 directly to a cheap USB to 5v adapter which is in a waterproof box. That adapter can then plug straight into a PC or Raspberry pi depending on what we want to do.
When we use astroberry, we run it on a raspberry pi along with ser2net talking to the USB serial port.
This exposes the serial data on udp port 10880. So whenever the astroberry server is up, you can connect to its network through the wifi ap or the lan and use the android syscan pro app to control the mount. Be aware that bad things happen if you use android synscan at the same time as indi is talking to the mount, as the two interfere. Nothing breaks, but they both get confused about where the mount is.
Furthermore, the mount is configured within kstars and ekos, and when that’s running, the skysafari indi driver is active so you can use skysafari from a phone as well.
Or you can run synscan pro and tell it your telescope mount is a synscan at :10882 and as long as synscan pro is running it should just work.
it would be nice to get bluetooth from the phone to the mount too, as that would allow the phone to talk to the mount while retaining mobile data for internet access and without faffing around with hotspots.
More detail under the hood
The whole area is a bit complicated because there are a number of different protocols, programs etc available, and of course things change over time too. However, as of late 2023, it all works like this.
The HEQ5 itself understands a specific protocol over the serial connection through the RJ45 socket described above. This protocol, referred to as the ‘mount protocol’ below, is used by the synscan hand controller which plugs into the HEQ5 direct, and that is the usual setup when you first buy a mount.
The black synscan handset itself has a 6 pin connector which can be used to interface directly to a serial port as it does the necessary level conversion. By default, this understands a ‘synscan controller’ protocol, which is more high-level than the ‘mount protocol’ and is typically the protocol used by consumer-oriented astro software.
So, the ‘usual’ setup would consist of an HEQ5 connected to a Synscan handset connected to a serial port on a PC interfacing to a telescope control inside a program like stellarium.
But there are alternatives, which eliminate the need for the synscan controller, and also allow you to interface over bluetooth or wifi.
You can buy a Synscan Wifi Adapter dongle which exposes the mount protocol over wifi. This plugs directly into the mount and listens typically on udp port 10880. Or, rather than forking out about £50, you can build a cable for about £5 which gives you USB. Although we currently use astroberry on a full raspberry pi, you could just connect the USB to a pi zero running ser2net, which then means that you have home-built the Wifi Adapter dongle for under £20.
You can then run, on PC or android, a free program called syscan_app_pro, which can connect to a synscan either via a serial cable or over the wifi protocol and emulates the hand controller. This also exposes the syscan controller protocol on port 10882, which allows telescope software build for that protocol to talk to the mount.
This allows android programs like sky-safari, or windows programs like stellarium to control the mount without any cables and without needing a synscan controller.
It’s worth pointing out that there’s no need for the synscan_app to run on the same machine as the telescope controller as long as all the ip addresses are set up properly.
Ascom and eqmod
Ascom is a framework for control of multiple different kinds of astronomical equipment, in particular including mounts. It runs on PC and uses hardware specific drivers to interface to a telescope. Planetarium software can connect to it and thus interface to hardware without knowing the details of the underlying hardware protocol.
There are two useful ascom drivers available for the mount. One of them is serial port based and allows a PC with a physical serial port to connect directly to the mount. The other is ip based and connects to the telescope via the synscan app ( which as explained above in turn requires the mount use a wifi dongle ).
Eqmod is a program which uses ascom to provide an interactive control panel for a telescope. It’s not needed if you’re using a planetarium program or the user interface of synscan.
Indi
Indi does what Ascom does in the Linux world. The astroberry setup configures indi via EKOS which is included in kstars, giving you a fully functioning planetarium with telescope control etc. available via vnc web interface on port 80
