Kramer Electronics SP-14 - Manual (Page 5)

avPar_chCurr_pipSizeXY 50 ms
avPar_outputDisplay * 300 ms
avPar_outputGammaMode 250 ms
avPar_pictureFormat 150 ms
* This parameter has proved to be particularly troublesome and unpredictable with regard to the
delay. It is recommended that special attention be paid and err on the side of caution.
3 API Functions
All communications to the unit have fixed request packet size of 16 bytes. There are different reply
packets for the class of function. All are fixed length except when a string is returned, these are
intrinsically variable in size. See 3.2.2 Parameter Reply Packet format for details.
Some functions will cause the unit to reboot and this will break the communication link. The user
interface designer will need to consider this scenario as part of the user interface design or document
accordingly.
3.1 Identity
The identity function provides the ability to test that the unit being controlled understands the AV API
protocol that this document refers.
3.1.1 Identity Request Packet format
The identity packet is filled with ASCII uppercase ‘A’s.
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‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’ ‘A’
3.1.2 Identity Reply Packet
The reply packet is variable in size depending on the reply. For Ethernet the reply packet may be
padded for performance purposes. The host should expect to receive at least 1024 bytes and allocate
a buffer large enough.
A unit understanding this protocol will return the following ASCII string (here: FoveaHD):
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‘ V’ ‘ X’ ‘ L’ ‘ 5’ ‘ 0’ ‘ 0’ ‘ H’ ‘ D’
(This refers to the protocol software and not the physical units’ product or model).
It is envisaged that protocol revision will be made available also, to enable the pairing of firmware with
remote control software.
3.2 Parameter Functions
The AV API parameter functions provide a means to query and control the unit remotely.
3.2.1 Parameter Request Packet format
The parameter request packet takes the following format:
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‘A’ ‘P’ fun paramID attribute value ‘A’
Where
‘A’, ‘P’ are literal ASCII characters.
fun is the function identifier.
paramID is the parameter identifier.
attribute is the attribute identifier.
value is a value.