---
name: "rotctl"
section: "1"
platform: "linux"
package: "hamlib"
version: "4.7.2-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/rotctl"
---

# rotctl(1)

control antenna rotators

## NAME

rotctl - control antenna rotators

## SYNOPSIS

**rotctl** \[**-hiIlLuV**\] \[**-m** *id*\] \[**-r** *device*\] \[**-R** *device2*\] \[**-s** *baud*\] \[**-t** *char*\] \[**-C** *parm=val*\] \[**-o** *azoffset*\] \[**-O** *eloffset*\] \[**-v**\[**-Z**\]\] \[**command**\|**-**\]

## DESCRIPTION

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.

## OPTIONS

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:

- **-m**, **--model**=***id***

  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**).

- **-r**, **--rot-file**=***device***

  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.

- **-R**, **--rot-file2**=***device***

  Use *device* as the file name of the port connected to the 2nd rotator. e.g. 2nd rotator used for elevation.

-

  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.

- **-s**, **--serial-speed**=***baud***

  Set serial speed to *baud* rate.

-

  Uses maximum serial speed from rotator backend capabilities as the default.

- **-t**, **--send-cmd-term**=***char***

  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.

- **-o**, **--set-azoffset**

  Azimuth correction floating point -- during set value is added, during get value is subtracted.

- **-O**, **--set-eloffset**

  Elevation correction floating point -- during set value is added, during get value is subtracted.

- **-L**, **--show-conf**

  List all configuration parameters for the rotator defined with **-m** above.

- **-C**, **--set-conf**=***parm=val***\[***,parm=val***\]

  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.

- **-u**, **--dump-caps**

  Dump capabilities for the rotator defined with **-m** above and exit.

- **-l**, **--list**

  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)](/more/1.md) or [**less**(1)](/less/1.md), e.g. “rotctl -l \| more”.

- **-i**, **--read-history**

  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.

- **-I**, **--save-history**

  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.

- **-v**, **--verbose**

  Set verbose mode, cumulative (see **DIAGNOSTICS** below).

- **-Z**, **--debug-time-stamps**

  Enable time stamps for the debug messages.

-

  Use only in combination with the **-v** option as it generates no output on its own.

- **-h**, **--help**

  Show a summary of these options and exit.

- **-V**, **--version**

  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

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
>.EOF.
$ rotctl -m 1 - <cmds.txt
set_pos 180.0 10.0
pause 30
get_pos 180.000000
10.000000
$
```

### 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.):

- **Q**\|**q**, exit rotctl

  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.

- **P**, **set\_pos** '***Azimuth***' '***Elevation***'

  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*'.

- **p**, **get\_pos**

  Get position.

-

  '*Azimuth*' and '*Elevation*' are returned as double precision floating point values.

- **M**, **move** '***Direction***' '***Speed***'

  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, ‘16’ = RIGHT or CW, ‘32’ = UP\_LEFT or UP\_CCW, ‘R64’ = UP\_RIGHT = UP\_CW, ‘128’ = DOWN\_LEFT or DOWN\_CCW, ‘256’ = DOWN\_RIGHT or DOWN\_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.

- **S**, **stop**

  Stop the rotator.

- **K**, **park**

  Park the rotator.

- **C**, **set\_conf** '***Token***' '***Value***'

  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.

- **R**, **reset** '***Reset***'

  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.

- **dump\_state**

  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.

- **w**, **send\_cmd** '***Cmd***'

  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.

- **L**, **lonlat2loc** '***Longitude***' '***Latitude***' '***Loc Len***'

  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
  ```

-

  returns:

-

  ```
  Locator: AA55AA00AA00
  ```

- **l**, **loc2lonlat** '***Locator***'

  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
  ```

-

  returns:

-

  ```
  Longitude: -169.999983 Latitude: -84.999991
  ```

-

  **Note**: Despite the use of double precision variables internally, some rounding error occurs.

- **D**, **dms2dec** '***Degrees***' '***Minutes***' '***Seconds***' '***S/W***'

  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).

- **d**, **dec2dms** '***Dec Degrees***'

  Returns '*Degrees*' '*Minutes*' '*Seconds*' '*S/W*'.

-

  Values are as in **dms2dec** above.

- **E**, **dmmm2dec** '***Degrees***' '***Dec Minutes***' '***S/W***'

  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.

- **e**, **dec2dmmm** '***Dec Deg***'

  Returns '*Degrees*' '*Minutes*' '*S/W*'.

-

  Values are as in **dmmm2dec** above.

- **B**, **qrb** '***Lon 1***' '***Lat 1***' '***Lon 2***' '***Lat 2***'

  Returns '*Distance*' and '*Azimuth*'.

-

  '*Distance*' is in km.

-

  '*Azimuth*' is in degrees.

-

  Supplied *Lon*/*Lat* values are signed floating point numbers.

- **A**, **a\_sp2a\_lp** '***Short Path Deg***'

  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.

- **a**, **d\_sp2d\_lp** '***Short Path km***'

  Returns '*Long Path km*'.

-

  Both the supplied argument and returned value are floating point values.

- **pause** '***Seconds***'

  Pause for the given whole (integer) number of '*Seconds*' before sending the next command to the rotator.

## READLINE

If **Readline** library development files are found at configure time, **rotctl** will be conditionally built with Readline support for command and argument entry. Readline command key bindings are at their defaults as described in the Readline manual ⟨https://tiswww.cwru.edu/php/chet/readline/rluserman.html⟩. **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 ⟨https://tiswww.case.edu/php/chet/readline/history.html#SEC1⟩. 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.

## DIAGNOSTICS

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.

## EXIT STATUS

**rotctl** exits with:

- **0**

  if all operations completed normally;

- **1**

  if there was an invalid command line option or argument;

- **2**

  if an error was returned by **Hamlib**.

## EXAMPLES

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 \get_pos
```

Start **rotctl** for INDI using an address other than the default *localhost:5764*:

```
$ rotctl -m 2001 -r example.com:12345
```

Start **rotctl** for INDI using the local domain on Linux:

```
$ rotctl -m 2001 -r @/tmp/indiserver
```

INDI (Instrument Neutral Distributed Interface) is an LGPLv2 software to control astronomical equipment, including telescope mounts that can be used to rotate antennas.

For more information see indilib.org ⟨https://indilib.org/⟩

## BUGS

Report bugs to:

-

  ```
  Hamlib Developer mailing list
  ⟨hamlib\-developer@lists.sourceforge.net⟩
  ```

## COPYING

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.

## SEE ALSO

[**less**(1)](/less/1.md), [**more**(1)](/more/1.md), [**rotctld**(1)](/rotctld/1.md), [**hamlib**(7)](/hamlib/7.md)

## COLOPHON

Links to the Hamlib Wiki, Git repository, release archives, and daily snapshot archives are available via hamlib.org ⟨http://www.hamlib.org⟩.