Stimulus Server communications protocol

Control commands list

These commands are sent from a control machine to the stimulus server, over a UDP channel.

SS PRESENT

This command is used to begin presentation of a pre-defined stimulus ID. Stimuli IDs are defined on the stimulus presentation machine, when the server is initialised.

SS PRESENT nStimID tPreBlankTime(seconds)
SS PRESENT nStimID tPreBlankTime(seconds) nNumExtraPresentArgs nNumExtraStimArgs ...

The first command syntax presents a pre-defined stimulus with no extra arguments. The second command syntax allows the triggering machine to define some of the stimulus parameters on the fly, as long as this is supported by the stimulus presentation command. See Building stimuli lists for more information.

SS KILL

This command is used to abort the server and immediately stop stimulus display if possible.

SS KILL

SS SHUTDOWN

This command shuts down the stimulus server nicely.

SS SHUTDOWN

SS LISTEN_PORT

This command causes the stimulus server to change the UDP port used to listen for commands.

SS LISTEN_PORT nPortNumber

SS TALKBACK_ADDRESS

This command causes the stimulus server to send talkback information to a new UDP host and port.

SS TALKBACK_ADDRESS strAddress nPortNumber

'strAddress' defines the hostname or IP address of the new talkback recipient machine. 'nPortNumber' is the receiving UDP port on the recipient machine.

SS LOGGING

This command allows remote configuration of the logging performed by the stimulus server. Logging can occur to a local file on the stimulus server machine, or to a remote machine over UDP.

SS LOGGING strFilename
SS LOGGING strAddress nPortNumber

The first command syntax causes the stimulus server to begin logging to the file 'strFilename'. The second command syntax causes the stimulus server to begin sending logging information over a UDP channel to the machine:port specified by 'strAddress':'nPortNumber'.

Talkback information

The stimulus server can optionally provide feedback about the current status and actions of the server. The strings listed here are sent over UDP to an optional talkback recipient machine.

SST HELLO

This string indicates that a talkback channel is now opened.

SST HELLO

SST RUNNING

SST RUNNING fVersion

A stimulus server is now running, with version number 'fVersion'.

SST LISTEN

SST LISTEN nListenPort

A stimulus server is now listening on UDP port 'nListenPort'.

SST IDLE

SST IDLE

The stimulus server is idle, and waiting for a command.

SST PRESENT

SST PRESENT nStimID

A stimulus will be presented, with ID 'nStimID'.

SST SEQ

SST SEQ nSeqStimID

An element of a sequence will be presented, with sequence ID 'nSeqStimID'.

SST SHUTDOWN

SST SHUTDOWN

The stimulus server is shutting down.

SST ABORT

SST ABORT

The stimulus server aborted.

SST CMDERROR

SST CMDERROR

An invalid command was received over the command channel.

SST FAILED

SST FAILED

A command could not be executed successfully.