Control the Rotator with the S.A.T. or PstRotator
SkyRoof moves the antenna by sending azimuth and elevation to a server that speaks the rotctld protocol over TCP. In the usual arrangement, described in Setting Up Rotator Control, that server is rotctld.exe from HamLib. Two popular alternatives speak the same protocol themselves, so rotctld.exe is not needed at all:
- the S.A.T. satellite tracker from CSN Technologies, which appears on your network as a Hamlib rotator server;
- PstRotator by YO3DMU, which has a built-in rotctld server.
In both cases SkyRoof predicts the pass and computes the bearings, and the device or the program moves the rotator. This section covers rotator control only — the radio is still tuned by SkyRoof as described in Setting Up CAT Control.
Which Option to Use
From inside SkyRoof the three arrangements are identical: the same three settings, the same Rotator Control panel, the same rotation algorithm, and the same manual pointing, parking and stop commands. They differ in what is wired to the rotator controller, and in what you have to start and keep running:
| rotctld.exe | S.A.T. | PstRotator | |
|---|---|---|---|
| Wired to the rotator controller | a COM port of the computer that runs SkyRoof | the S.A.T., over its own cable | a COM port of the computer that runs PstRotator |
| Controllers supported | the HamLib list | Yaesu G-5400 / G-5500 / G-5600 and PstRotator, and SPID in the recent firmware | the PstRotator list |
| To start before a session | the rotctld.exe console window | nothing, the S.A.T. always listens | the PstRotator window |
| Pointing the antenna when SkyRoof is not running | not possible, rotctld.exe has no user interface | from the S.A.T. web page or its front panel | from the PstRotator window |
| Cost | free | the price of the device | the price of the license |
Use rotctld.exe when the rotator controller is cabled to the computer that runs SkyRoof and HamLib supports it. This is the shortest path from SkyRoof to the rotator — one program, one shortcut, nothing to buy — and it is the arrangement described in Setting Up Rotator Control.
Use the S.A.T. when you already own one, or when the rotator controller is not near the computer: the S.A.T. sits at the rotator and is reached over the network, and it also tracks satellites and parks the antenna on its own when SkyRoof is not running. Its built-in tracker must stay idle while SkyRoof is tracking.
Use PstRotator when you already run it for your other antennas, when your rotator controller is supported by PstRotator but not by HamLib, or when you want its maps and its manual controls at hand during a pass. It is the only one of the three that costs a license fee if you do not already use it.
Each of these puts one program or device between SkyRoof and the rotator. Longer chains are possible — the S.A.T. can drive PstRotator, and rotctld.exe can drive PstRotator through its UDP interface — but every added link is one more place where the bearings can stop flowing, so build one only when the rotator controller cannot be reached any other way.
Using the S.A.T.
The S.A.T. listens for rotator commands on TCP port 4533, and this server is enabled by default, so no setting has to be changed to turn it on.
In the S.A.T. web interface open the ROTATOR panel, set TYPE to your rotator model, set the travel limits and the park and ready positions as usual, and click SAVE.
Open the NETWORK panel and note the IP address of the S.A.T. It is also shown on the S.A.T. display. The PORTS fields on the same panel show which ports the S.A.T. listens on; leave the rotator port at 4533 unless it conflicts with something else on your network.
Make sure the antenna is enabled in the S.A.T. — the ANT ENABLE button flashes red when it is not.
Do not start tracking on the S.A.T. itself. SkyRoof and the built-in tracker of the S.A.T. would then send conflicting bearings to the same rotator. Let the S.A.T. sit idle and leave the tracking to SkyRoof.
In SkyRoof, click Tools / Settings and set, in the Rotator section:
- Host - the IP address of the S.A.T.;
- TCP Port - 4533;
- Enabled - True.
SkyRoof uses only three rotctld commands - set the position, read the position and stop - and these are exactly the commands that the S.A.T. implements. Other tracking programs may require a more complete Hamlib implementation and have to reach the S.A.T. through a HamLib backend; SkyRoof connects to it directly.
Set Minimum Azimuth, Maximum Azimuth, Minimum Elevation and Maximum Elevation in the SkyRoof settings to the same travel limits that you configured in the S.A.T., so that SkyRoof does not ask for a bearing that the rotator cannot reach.
Using PstRotator
Before you connect SkyRoof, configure PstRotator for your rotator controller and check in the Manual mode that it moves the antenna. SkyRoof only supplies the bearings; everything about the controller itself stays in PstRotator.
PstRotator listens on TCP port 4533 and SkyRoof connects to it directly. Its rotctld server has been part of the program since version 14.93.
In PstRotator, open the Setup menu and check Rotctld Hamlib Server. The option is off in a new installation, and the program starts listening on port 4533 as soon as you check it.
Open Communication / Rotctld Server Setup..., and in the Rotctld Setup window check that Port number is 4533 and that Extended protocol is unchecked, which is how a new installation comes. SkyRoof expects the plain replies of the standard protocol. Click Save Settings to close the window.
Leave Mode set to Manual in the main window of PstRotator. The Manual / Tracking selector belongs to the trackers of PstRotator itself: with Tracking selected, the program follows whatever is chosen in its Tracker menu — the Moon in a new installation — and overrides the bearings that SkyRoof sends. The rotctld server accepts positions in either mode.
If your rotator can point higher than 90° in elevation, check 180 deg Elevation in the Setup menu, so that PstRotator accepts the flipped bearings that SkyRoof sends on high passes. Without this option PstRotator answers a flipped bearing with "RPRT 0" but silently moves to 90° instead of the elevation it was given.
In SkyRoof, click Tools / Settings and set, in the Rotator section:
- Host - "127.0.0.1" if PstRotator runs on the same computer as SkyRoof, or the address of the computer where it runs;
- TCP Port - 4533;
- Enabled - True.
The server of PstRotator accepts the set position, read position, stop and park commands, and SkyRoof uses the first three of them, so everything on the Rotator Control panel works, including the Stop button.
Do not run rotctld.exe at the same time. Both programs would try to listen on port 4533 and only one of them would get it.
Checking the Connection
Click on the Rotator label on the status bar to enable and disable rotator control, and watch the Rotator Control panel: the small numbers below the satellite position are the antenna bearing as reported by the S.A.T. or by PstRotator. If they follow the satellite, the connection works. A pink color on the panel means that the antenna is not pointing where SkyRoof asked it to.
If nothing moves, set Log Traffic to True in the Rotator settings, reproduce the problem, and look at the log file in the data folder to see the commands and the replies.