Tesira Text Protocol

Expected responses

For simple TTP set commands Tesira will return a +OK message.

Level3 set level 2 0

+OK

Get commands illicit a response. 

Level3 get level 2

+OK "value":0.000000

-ERR responses

If there is a missing or incorrect part of the string sent in the TTP command Tesira will return an error message. The message will typically indicate where in the string the fault was found, or which parameter is invalid. The invalid parameter message can be daunting at first but is generally a straight-forward issue to resolve. 

Common errors are missing or added spaces between terms, instance tag mismatch, or the specified control value is not valid for the control object (e.g. - trying to control channel 3 in a 2 channel level control block, or trying to set a level control to +20 when the max limit is +12)

level3 set mute 3 true

-ERR address not found: {"deviceId":0 "classCode":0 "instanceNum":0}

Verify that the instance tag is correct. You can send the query "SESSION get aliases" to return a list of get a listing of available Instance Tags via TTP or check the Tesira configuration file. Here we can see that the name "level3" was incorrect, "Level3" was correct - capitalization and spaces matter in TTP commands.

SESSION get aliases

+OK "list":["AecInput1" "AudioMeter2" "AudioMeter4" "DEVICE" "DanteInput1" "DanteOutput1" "Level1" "Level2" "Level3" "Mixer1" "NoiseGenerator1" "Output1" "Router1" "ToneGenerator1" "ToneGenerator2" "USBInput1" "USBOutput1"]

Here the instance tag is correct but the channel index value is not valid. 1 or 2 would be legal.

Level3 set mute 3 true

-ERR INVALID_PARAMETER Index out of range:channelIndex min:1 max:2 received:3

In a ganged level or mute control block the channel ID is 0, but for an un-ganged block the channel number of interest must be used. Here 0 is used in an un-ganged level control block. The correct channel index value must be used. 1 or 2 would be legal.

Level3 set mute 0 true

-ERR INVALID_PARAMETER Index out of range:channelIndex min:1 max:2 received:0

All control commands required by the TTP string must be sent

Level3 set mute

-ERR Parse error at 15: not enough parameters supplied

Correct formatting is important, leaving out a space where one is required will generate a fault.

Level3 set level1 1

-ERR 'level1' is not supported by LevelControlInterface::Attributes

Subscription responses

All Subscription responses are preceded by a ! “publishToken” statement when using TTP in Verbose Mode (default mode) *. This is to indicate to the control system that the returned packet is from a subscription response, not just a reply to a singular command. Using the TTP subscription example command above, the responses would look like this:

MyLevel1 subscribe level 1 MyCustomLabel 500
! “publishToken”:”MyLevelCustomLabel” “value”:-100.000000
! “publishToken”:”MyLevelCustomLabel” “value”:-98.099998
! “publishToken”:”MyLevelCustomLabel” “value”:-77.800003

The responses above show the subscription to a single channel. If a multi-channel DSP object is used, by changing the attribute field, multiple channels can be made to report within one response.  Note that this example subscribes to the "levels" parameter rather than the "level" parameter.

MyLevel1 subscribe levels MyCustomLabel 500
! “publishToken”:”MyLevelCustomLabel” “value”:[-100.000000 0.000000  4.000000 -12.000000]
! “publishToken”:”MyLevelCustomLabel” “value”:[ -98.099998  0.000000  4.000000 -12.000000]
! “publishToken”:”MyLevelCustomLabel” “value”:[ -77.800003  0.000000  4.000000 -12.000000]

Subscriptions are lost when the Tesira server is rebooted however they can be recreated by subscribing to the same block at regular intervals. Ensure that the same Custom Label is used in the re-subscription otherwise multiple sessions to the same object may be inadvertently opened. Consideration should be given to buffer sizes to make sure all of the subscribed responses can be processed by the control system. If a Subscription is no longer needed an ‘unsubscribe’ command can be issued to reduce the load on the control processor.

* If non-verbose responses are required, the mode should be changed before any subscriptions are made. The response type for each subscription is fixed according to the mode that was active at the time the subscription was made. 

Camera tracking example

Monitoring level changes example

Meter subscription example

Call Progress for telephone interfaces example