--- name: "ampctld" section: "1" platform: "linux" package: "hamlib" version: "4.7.2-2" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/ampctld" --- # ampctld(1) TCP amplifier control daemon ## NAME ampctld - TCP amplifier control daemon ## SYNOPSIS **ampctld** \[**-hlLuV**\] \[**-m** *id*\] \[**-r** *device*\] \[**-s** *baud*\] \[**-T** *IPADDR*\] \[**-t** *number*\] \[**-C** *parm=val*\] \[**-v**\[**-Z**\]\] ## DESCRIPTION The **ampctld** program is an amplifier control daemon that handles client requests via TCP sockets. This allows multiple user programs to share one amplifier (this needs more development). Multiple amplifiers can be controlled on different TCP ports by use of multiple **ampctld** processes. Note that multiple processes/ports are also necessary if some clients use extended responses and/or vfo mode. So up to 4 processes/ports may be needed for each combination of extended response/vfo mode. The syntax of the commands are the same as [**ampctl**(1)](/ampctl/1.md). It is hoped that **ampctld** will be especially useful for client authors using languages such as Perl, Python, PHP, and others. **ampctld** communicates to a client through a TCP socket using text commands shared with **ampctl**. The protocol is simple, commands are sent to **ampctld** on one line and **ampctld** responds to **get** commands with the requested values, one per line, when successful, otherwise, it responds with one line “RPRT x”, where ‘x’ is a negative number indicating the error code. Commands that do not return values respond with the line “RPRT x”, where ‘x’ is ‘0’ when successful, otherwise is a negative number indicating the error code. Each line is terminated with a newline ‘\\n’ character. This protocol is primarily for use by the **NET ampctl** (amplifier model 2) backend. A separate **Extended Response Protocol** extends the above behavior by echoing the received command string as a header, any returned values as a key: value pair, and the “RPRT x” string as the end of response marker which includes the **Hamlib** success or failure value. See the **PROTOCOL** section for details. Consider using this protocol for clients that will interact with **ampctld** directly through a TCP socket. Keep in mind that Hamlib is BETA level software. While a lot of backend libraries lack complete amplifier 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 amplifier model number. - See model list (use “ampctl -l”). - **Note**: **ampctl** (or third party software using the C API) will use amplifier model 2 for **NET ampctl** (communicating with **ampctld**). - **-r**, **--amp-file**=***device*** Use *device* as the file name of the port connected to the amplifier. - 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 amplifier backend capabilities (set by **-m** above) as the default. - **-t**, **--port**=***number*** Use *number* as the TCP listening port. - The default is 4531. - **Note**: As **rigctld**'s default port is 4532 and **rotctld**'s default port is 4533, it is recommended to use DESCENDING odd numbered ports for multiple **ampctld** instances, e.g. 4529, 4527, 4525, etc. - **-T**, **--listen-addr**=***IPADDR*** Use *IPADDR* as the listening IP address. - The default is ANY. - **-L**, **--show-conf** List all config parameters for the amplifier defined with **-m** above. - **-C**, **--set-conf**=***parm=val***\[***,parm=val***\] Set amplifier 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 amplifier defined with **-m** above and exit. - **-l**, **--list** List all amplifier 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. “ampctl -l \| more”. - **-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 **ampctl** and exit. **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. Please note that the backend for the amplifier to be controlled, or the amplifier itself may not support some commands. In that case, the operation will fail with a **Hamlib** error code. ## COMMANDS Commands can be sent over the TCP socket either as a single char, or as a long command name plus the value(s) space separated on one ‘\\n’ terminated line. See **PROTOCOL**. Since most of the **Hamlib** operations have a **set** and a **get** method, an upper case letter will be used for **set** methods whereas the corresponding lower case letter refers to the **get** method. Each operation also has a long name; prepend a backslash, ‘\\’, to send a long command name. Example (Perl): “print $socket "\\\\dump\_caps\\n";” to see what the amplifier's backend can do (**Note**: In Perl and many other languages a ‘\\’ will need to be escaped with a preceding ‘\\’ so that even though two backslash characters appear in the code, only one will be passed to **ampctld**. This is a possible bug, beware!). **Note**: The backend for the amplifier to be controlled, or the amplifier itself may not support some commands. In that case, the operation will fail with a **Hamlib** error message. Here is a summary of the supported commands (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.): - **F**, **set\_freq** '***Frequency***' Set '*Frequency*', in Hz. - Frequency may be a floating point or integer value. - **f**, **get\_freq** Get '*Frequency*', in Hz. - Returns an integer value. - **l**, **get\_level** '***Level***' Get '*Level Value*'. - Returns Level Value as a float or integer for the Level token given. - **Note**: Passing a ‘?’ (query) as the first argument instead of a Level token will return a space separated list of amplifier backend supported get level tokens. Use this to determine the supported levels of a given amplifier backend. - **dump\_state** Return certain state information about the amplifier backend. - **1**, **dump\_caps** Not a real amplifier remote command, it just dumps capabilities, i.e. what the backend knows about this model, and what it can do. - TODO: Ensure this is in a consistent format so it can be read into a hash, dictionary, etc. Bug reports requested. - **Note**: This command will produce many lines of output so be very careful if using a fixed length array! For example, running this command against the Dummy backend results in a number of lines of text output. - **\_**, **get\_info** Return information from the amplifier backend. - **R**, **reset** '***Reset***' Perform amplifier '*Reset*'. - Reset is an integer value: ‘0’ = None, ‘1’ = Memory reset, ‘2’ = Fault reset, ‘3’ = Amplifier reset. - **set\_powerstat** '***Power Status***' Set '*Power Status*'. - Power Status is an integer value: ‘0’ = Power Off, ‘1’ = Power On, ‘2’ = Power Standby (enter standby), ‘4’ = Power Operate (leave standby). - **get\_powerstat** Get '*Power Status*' as in **set\_powerstat** above. ## PROTOCOL There are two protocols in use by **ampctld**, the **Default Protocol** and the **Extended Response Protocol**. The **Default Protocol** is intended primarily for the communication between **Hamlib** library functions and **ampctld** (“NET ampctl”, available using amplifier model ‘2’). The **Extended Response Protocol** is intended to be used with scripts or other programs interacting directly with **ampctld** as consistent feedback is provided. ### Default Protocol The **Default Protocol** is intentionally simple. Commands are entered on a single line with any needed values. In practice, reliable results are obtained by terminating each command string with a newline character, ‘\\n’. Example set frequency and mode commands (Perl code (typed text shown in bold)): ``` print $socket "F 14250000\n"; print $socket "\\set_powerstat 1\n"; # escape leading '\' ``` A one line response will be sent as a reply to **set** commands, “RPRT *x*\\n” where *x* is the Hamlib error code with ‘0’ indicating success of the command. Responses from **ampctld** **get** commands are text values and match the same tokens used in the **set** commands. Each value is returned on its own line. On error the string “RPRT *x*\\n” is returned where *x* is the Hamlib error code. Example get frequency (Perl code): ``` print $socket "f\n"; "14250000\n" ``` Most **get** functions return one to three values. A notable exception is the **dump\_caps** command which returns many lines of **key**:*value* pairs. This protocol is primarily used by the “NET ampctl” (ampctl model 2) backend which allows applications already written for Hamlib's C API to take advantage of **ampctld** without the need of rewriting application code. An application's user can select amplifier model 2 (“NET ampctl”) and then set **amp\_pathname** to “localhost:4531” or other network *host*:*port* (set by the **-T**/**-t** options, respectively, above). ### Extended Response Protocol The Extended Response protocol adds several rules to the strings returned by **ampctld** and adds a rule for the command syntax. 1\. The command received by **ampctld** is echoed with its long command name followed by the value(s) (if any) received from the client terminated by the specified response separator as the first record of the response. 2\. The last record of each block is the string “RPRT *x*\\n” where *x* is the numeric return value of the Hamlib backend function that was called by the command. 3\. Any records consisting of data values returned by the amplifier backend are prepended by a string immediately followed by a colon then a space and then the value terminated by the response separator. e.g. “Frequency: 14250000\\n” when the command was prepended by ‘+’. 4\. All commands received will be acknowledged by **ampctld** with records from rules 1 and 2. Records from rule 3 are only returned when data values must be returned to the client. An example response to a **set\_frequency** command sent from the shell prompt (note the prepended ‘+’): ``` $ echo "+F 14250000" | nc -w 1 localhost 4531 set_freq: 14250000 RPRT 0 ``` In this case the long command name and values are returned on the first line and the second line contains the end of block marker and the numeric amplifier backend return value indicating success. An example response to a **get\_freq** query: ``` $ echo "+\get_freq" | nc -w 1 localhost 4531 get_freq: Frequency(Hz): 14250000 RPRT 0 ``` - **Note**: The ‘\\’ is still required for the long command name even with the ERP character. In this case, as no value is passed to **ampctld**, the first line consists only of the long command name. The final line shows that the command was processed successfully by the amplifier backend. Invoking the Extended Response Protocol requires prepending a command with a punctuation character. As shown in the examples above, prepending a ‘+’ character to the command results in the responses being separated by a newline character (‘\\n’). Any other punctuation character recognized by the C **ispunct**() function except ‘\\’, ‘?’, or ‘\_’ will cause that character to become the response separator and the entire response will be on one line. Separator character summary: - ‘**+**’ Each record of the response is appended with a newline (‘\\n’). - ‘**;**’, ‘**\|**’, or, ‘**,**’ Each record of the response is appended by the given character resulting in entire response on one line. - These are common record separators for text representations of spreadsheet data, etc. - ‘**?**’ Reserved for help in **ampctl**. - ‘**\_**’ Reserved for **get\_info** short command - ‘**#**’ Reserved for comments when reading a command file script. - **Note**: Other punctuation characters have not been tested! Use at your own risk. For example, invoking a **get\_freq** query with a leading ‘;’ returns: ``` get_freq:;Frequency(Hz): 14250000;RPRT 0 ``` Or, using the pipe character ‘\|’ returns: ``` get_freq:|Frequency(Hz): 14250000|RPRT 0 ``` And a **set\_freq** command prepended with a ‘\|’ returns: ``` set_freq: 14250000|RPRT 0 ``` Such a format will allow reading a response as a single event using a preferred response separator. Other punctuation characters have not been tested! ## 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 amplifier which is very useful for amplifier backend library development and may be requested by the developers. ## EXAMPLES Start **ampctld** for an Elecraft KPA-1500 using a USB-to-serial adapter and backgrounding: ``` $ ampctld -m 201 -r /dev/ttyUSB1 & ``` Start **ampctld** for an Elecraft KPA-1500 using COM2 on MS Windows: ``` $ ampctld -m 201 -r COM2 ``` Connect to the already running **ampctld** and set the frequency to 14.266 MHz with a 1 second read timeout using the default protocol from the shell prompt: ``` $ echo "\set_freq 14266000" | nc -w 1 localhost 4531 ``` Connect to a running **ampctld** with **ampctl** on the local host: ``` $ ampctl -m2 ``` ## SECURITY No authentication whatsoever; DO NOT leave this TCP port open wide to the Internet. Please ask if stronger security is needed or consider using a Secure Shell ([**ssh**(1)](/ssh/1.md)) tunnel. As **ampctld** does not need any greater permissions than **ampctl**, it is advisable to not start **ampctld** as “root” or another system user account in order to limit any vulnerability. ## BUGS The daemon is not detaching and backgrounding itself. No method to exit the daemon so the [**kill**(1)](/kill/1.md) command must be used to terminate it. Multiple clients using the daemon may experience contention with the connected amplifier. 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 © 2000-2010 Stephane Fillod\ Copyright © 2000-2018 the Hamlib Group (various contributors)\ Copyright © 2011-2020 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 [**kill**(1)](/kill/1.md), [**ampctl**(1)](/ampctl/1.md), [**ssh**(1)](/ssh/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⟩.