Kramer Electronics VP-790 - Manual (Page 11)

VP-790 Protocol – Communication 7
For the API call the data is 0 = 0x00 bytes long since there are no parameters
passed. The data package (line 3) is 12 bytes long plus the length of the data.
Therefore, the application header (line 2) indicates a payload of 12 + 0 = 0x0C
bytes. The logical header (line 1) indicates a payload of 16 bytes application header
plus 12 bytes of the data package, i.e. 28 = 0x1C bytes.
Direction RS232 data
PC sends command 53 41 50 01 FF FF FF FF 00 00 00 1C 00 00 00 00
54 50 01 00 00 00 00 00 00 00 00 0C 00 00 00 00
50 46 00 7D 00 00 00 00 00 00 00 00
Board acknowledges to have received
a command
73 61 50 01 FF FF FF FF 00 00 00 00 00 00 00 00
Board sends answer (return values) 53 41 50 01 FF FF FF FF 00 00 00 1D 00 00 00 00
74 50 01 00 00 00 00 00 00 00 00 0D 00 00 00 00
70 46 00 7D 00 00 00 00 00 00 00 01 00
PC acknowledges to have received an
answer
73 61 50 01 FF FF FF FF 00 00 00 00 00 00 00 00
Direction TCP/IP data
PC sends command 54 50 01 00 00 00 00 00 00 00 00 0C 00 00 00 00
50 46 00 7D 00 00 00 00 00 00 00 00
Board acknowledges to have received
a command
None
Board sends answer (return values) 74 50 01 00 00 00 00 00 00 00 00 0D 00 00 00 00
70 46 00 7D 00 00 00 00 00 00 00 01 00
PC acknowledges to have received an
answer
None
1.7.3
129B
Read the Contrast Setting
The API byOSDContrastGet is used to read the current contrast setting.
The API Index is decimal 126, i.e. hexadecimal 0x00 7E . There is one parameter
passed to the API function which is the retrieval method. The type of the parameter
is BYTE, i.e. 1 byte long. The retrieval method indicates from where the contrast
setting is to be read. That can be either from the system parameter database (SPD)
which is stored in non-volatile memory or from cache which carries the latest
contrast setting. The value in the SPD and cache can differ, if a change was issued
by calling byOSDContrastSet which was not yet stored in non-volatile memory by
calling byOSDContrastSave. Let us assume we want to read the SPD value, the
parameter is
0x01 .