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ROTCTL(1) Hamlib Utilities ROTCTL(1)


rotctl - control antenna rotators


rotctl [-hiIlLuV] [-m id] [-r device] [-s baud] [-t char] [-C parm=val] [-v[-Z]] [command|-]


Control antenna rotators.

rotctl accepts commands from the command line as well as in interactive mode if none are provided on the command line.

Keep in mind that Hamlib is BETA level software. While a lot of backend libraries lack complete rotator support, the basic functions are usually well supported.

Please report bugs and provide feedback at the e-mail address given in the BUGS section below. Patches and code enhancements sent to the same address are welcome.


This program follows the usual GNU command line syntax. Short options that take an argument may have the value follow immediately or be separated by a space. Long options starting with two dashes (‘-’) require an ‘=’ between the option and any argument.

Here is a summary of the supported options:

Select rotator model number.
See model list (use “rotctl -l”).
Note: rotctl (or third party software using the C API) will use rotator model 2 for NET rotctl (communicating with rotctld).
Use device as the file name of the port connected to the rotator.
Often a serial port, but could be a USB to serial adapter. Typically /dev/ttyS0, /dev/ttyS1, /dev/ttyUSB0, etc. on Linux, COM1, COM2, etc. on MS Windows. The BSD flavors and Mac OS/X have their own designations. See your system's documentation.
Set serial speed to baud rate.
Uses maximum serial speed from rotator backend capabilities as the default.
Change the termination char for text protocol when using the send_cmd command.
The default value is ASCII CR (‘0x0D’). ASCII non-printing characters can be given as the ASCII number in hexadecimal format prepended with “0x”. You may pass an empty string for no termination char. The string “-1” tells rotctl to switch to binary protocol. See the send_cmd command for further explanation.
Note: The semicolon (‘;’) is a common terminator for rotators that accept ASCII character strings.
List all configuration parameters for the rotator defined with -m above.
Set rotator configuration parameter(s), e.g. stop_bits=2.
Use the -L option above for a list of configuration parameters for a given model number.
Dump capabilities for the rotator defined with -m above and exit.
List all rotator model numbers defined in Hamlib and exit.
The list is sorted by model number.
Note: In Linux the list can be scrolled back using Shift-PageUp/Shift-PageDown, or using the scrollbars of a virtual terminal in X or the cmd window in Windows. The output can be piped to more(1) or less(1), e.g. “rotctl -l | more”.
Read previously saved command and argument history from a file (default $HOME/.rotctl_history) for the current session.
Available when rotctl is built with Readline support (see READLINE below).
Note: To read a history file stored in another directory, set the ROTCTL_HIST_DIR environment variable, e.g. “ROTCTL_HIST_DIR=$HOME/tmp rotctl -i”. When ROTCTL_HIST_DIR is not set, the value of HOME is used.
Write current session (and any previous session(s), if -i option is also given) command and argument history to a file (default $HOME/.rotctl_history) at the end of the current session.
Complete commands with arguments are saved as a single line to be recalled and used or edited. Available when rotctl is built with Readline support (see READLINE below).
Note: To write a history file in another directory, set the ROTCTL_HIST_DIR environment variable, e.g. “ROTCTL_HIST_DIR=$HOME/tmp rotctl -I”. When ROTCTL_HIST_DIR is not set, the value of HOME is used.
Set verbose mode, cumulative (see DIAGNOSTICS below).
Enable time stamps for the debug messages.
Use only in combination with the -v option as it generates no output on its own.
Show a summary of these options and exit.
Show version of rotctl and exit.
Stop option processing and read commands from standard input.
See Standard Input below.

Note: Some options may not be implemented by a given backend and will return an error. This is most likely to occur with the --set-conf and --show-conf options.

Be aware that the backend for the rotator to be controlled, or the rotator itself may not support some commands. In that case, the operation will fail with a Hamlib error code.


Commands can be entered either as a single char, or as a long command name. The commands are not prefixed with a dash as the options are. They may be typed in when in interactive mode or provided as argument(s) in command line interface mode. In interactive mode commands and their arguments may be entered on a single line (typed text shown in bold):

P 123 45

Since most of the Hamlib operations have a set and a get method, an upper case letter will often be used for a set method whereas the corresponding lower case letter refers to the get method. Each operation also has a long name; in interactive mode, prepend a backslash, ‘\’, to enter a long command name.

Example: Use “\get_info” in interactive mode to see the rotator's information.

Note: The backend for the rotator to be controlled, or the rotator itself may not support some commands. In that case, the operation will fail with a Hamlib error message.

Standard Input

As an alternative to the READLINE interactive command entry or a single command for each run, rotctl features a special option where a single dash (‘-’) may be used to read commands from standard input (stdin). Commands must be separated by whitespace similar to the commands given on the command line. Comments may be added using the ‘#’ character, all text up until the end of the current line including the ‘#’ character is ignored.

A simple example:

$ cat <<.EOF. >cmds.txt
> # File of commands
> set_pos 180.0 10.0	# rotate
> pause 30  # wait for action to complete
> get_pos   # query rotator
$ rotctl -m 1 - <cmds.txt
set_pos 180.0 10.0
pause 30
get_pos 180.000000

Rotator Commands

A summary of commands is included below (In the case of set commands the quoted italicized string is replaced by the value in the description. In the case of get commands the quoted italicized string is the key name of the value returned.):

Exit rotctl in interactive mode.
When rotctl is controlling the rotator directly, will close the rotator backend and port. When rotctl is connected to rotctld (rotator model 2), the TCP/IP connection to rotctld is closed and rotctld remains running, available for another TCP/IP network connection.
Set position.
'Azimuth' and 'Elevation' are floating point values.
Azimuth can be -180 to 540 depending on the rotator to allow for rotators facing south and the capabilities of the rotator.
Elevation can be -20 to 210 depending on the rotator.
For example:

P 163.0 41.0

Note: If the rotator does not support setting elevation (most do not) supply “0.0” for 'Elevation'.
Get position.
'Azimuth' and 'Elevation' are returned as double precision floating point values.
Move the rotator in a specific direction at the given rate.
'Direction' is an integer or keyword defined as ‘2’ = UP, ‘4’ = DOWN, ‘8’ = LEFT or CCW and ‘16’ = RIGHT or CW
'Speed' is an integer between 1 and 100. Use -1 for no change to current speed.
Note: Not all backends that implement the move command use the Speed value.
Stop the rotator.
Park the rotator.
Set a configuration parameter.
'Token' is a string; see the -C option and the -L output.
'Value' is a string of up to 20 characters.
Reset the rotator.
'Reset' accepts an integer value of ‘1’ for “Reset All”.
_, get_info
Get miscellaneous information about the rotator.
Returns 'Info' “Model Name” at present.
Return certain state information about the rotator backend.
1, dump_caps
Not a real rot remote command, it just dumps capabilities, i.e. what the backend knows about this model, and what it can do.
Send a raw command string to the rotator.
ASCII CR (or --send-cmd-term value, see -t option) is appended automatically at the end of the command for text protocols. For binary protocols, enter hexadecimal values as “\0xAA\0xBB”.

Locator Commands

These commands offer conversions of Degrees Minutes Seconds to other formats, Maidenhead square locator conversions and distance and azimuth conversions.

Returns the Maidenhead 'Locator' for the given 'Longitude' and 'Latitude'.
Floating point values are supplied. The precision of the returned square is controlled by 'Loc Len' which should be an even numbered integer value between 2 and 12.
For example:

L -170.0 -85.0 12


Locator: AA55AA00AA00

Returns 'Longitude' and 'Latitude' in decimal degrees at the approximate center of the requested Maidenhead grid square.
'Locator' can be from 2 to 12 characters in length.
West longitude is expressed as a negative value.
South latitude is expressed as a negative value.
For example:

l AA55AA00AA00


Longitude: -169.999983 Latitude: -84.999991

Note: Despite the use of double precision variables internally, some rounding error occurs.
Returns 'Dec Degrees', a signed floating point value.
'Degrees' and 'Minutes' are integer values.
'Seconds' is a floating point value.
'S/W' is a flag with ‘1’ indicating South latitude or West longitude and ‘0’ North or East (the flag is needed as computers don't recognize a signed zero even though only the 'Degrees' value is typically signed in DMS notation).
Returns 'Degrees' 'Minutes' 'Seconds' 'S/W'.
Values are as in dms2dec above.
Returns 'Dec Degrees', a signed floating point value.
'Degrees' is an integer value.
'Dec Minutes' is a floating point value.
'S/W' is a flag as in dms2dec above.
Returns 'Degrees' 'Minutes' 'S/W'.
Values are as in dmmm2dec above.
Returns 'Distance' and 'Azimuth'.
'Distance' is in km.
'Azimuth' is in degrees.
Supplied Lon/Lat values are signed floating point numbers.
Returns 'Long Path Deg'.
Both the supplied argument and returned value are floating point values within the range of 0.00 to 360.00.
Note: Supplying a negative value will return an error message.
Returns 'Long Path km'.
Both the supplied argument and returned value are floating point values.
Pause for the given whole (integer) number of 'Seconds' before sending the next command to the rotator.


If Readline library development files are found at configure time, rotctl will be conditonally built with Readline support for command and argument entry. Readline command key bindings are at their defaults as described in the Readline manual. rotctl sets the name “rotctl” which can be used in Conditional Init Constructs in the Readline Init File ($HOME/.inputrc by default) for custom keybindings unique to rotctl.

Command history is available with Readline support as described in the Readline History manual. Command and argument strings are stored as single lines even when arguments are prompted for input individually. Commands and arguments are not validated and are stored as typed with values separated by a single space.

Normally session history is not saved, however, use of either of the -i/--read-history or -I/--save-history options when starting rotctl will cause any previously saved history to be read in and/or the current and any previous session history (assuming the -i and -I options are given together) will be written out when rotctl is closed. Each option is mutually exclusive, i.e. either may be given separately or in combination. This is useful to save a set of commands and then read them later but not write the modified history for a consistent set of test commands in interactive mode, for example.

History is stored in $HOME/.rotctl_history by default although the destination directory may be changed by setting the ROTCTL_HIST_DIR environment variable. When ROTCTL_HIST_DIR is unset, the value of the HOME environment variable is used instead. Only the destination directory may be changed at this time.

If Readline support is not found at configure time the original internal command handler is used. Readline is not used for rotctl commands entered on the command line regardless if Readline support is built in or not.

Note: Readline support is not included in the MS Windows 32 or 64 bit binary builds supplied by the Hamlib Project. Running rotctl on the MS Windows platform in the ‘cmd’ shell does give session command line history, however, it is not saved to disk between sessions.


The -v, --verbose option allows different levels of diagnostics to be output to stderr and correspond to -v for BUG, -vv for ERR, -vvv for WARN, -vvvv for VERBOSE, or -vvvvv for TRACE.

A given verbose level is useful for providing needed debugging information to the email address below. For example, TRACE output shows all of the values sent to and received from the radio which is very useful for radio backend library development and may be requested by the developers.


rotctl exits with:

if all operations completed normally;
if there was an invalid command line option or argument;
if an error was returned by Hamlib.


Start rotctl for RotorEZ using the first serial port on Linux:

$ rotctl -m 401 -r /dev/ttyS0

Start rotctl for RotorEZ using COM2 on MS Windows:

> rotctl -m 401 -r COM2

Connect to a running rotctld with rotator model 2 (“NET rotctl”) on the local host and specifying the TCP port, and querying the position:

$ rotctl -m 2 -r localhost:4533 t_pos


Report bugs to:

Hamlib Developer mailing list


This file is part of Hamlib, a project to develop a library that simplifies radio, rotator, and amplifier control functions for developers of software primarily of interest to radio amateurs and those interested in radio communications.

Copyright © 2001-2011 Stephane Fillod
Copyright © 2002-2017 the Hamlib Group (various contributors)
Copyright © 2003-2020 Nate Bargmann

This is free software; see the file COPYING for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


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