Maintenance And Servicing - Francis Searchlights Voyager 2 User Instruction & Installation Manual

10. Fault Status 2
11. Lamp software version.
12. Lamp type No.
13. CRC
ERROR CONTROL
Error control is supported by a CRC following each data packet. The CRC is
radix to 7 bits with a value between 0 and 127. The CRC is simply the addition
of all packets data values including the address and start byte (0xFF). For
example, if lamp 0 were commanded to run its focus motor the transmitted
data would be; - 0xFF, 0x90, 0x0B. The addition of these values gives 0x19A.
The CRC would therefore be this value radix to 7 bits to give a value of
0x1A.this value is the CRC and would be sent as the last byte of the packet.
DATA TIMING
Data packets can be sent up to 10 times per second. Each packet starts with
the lamp address which is the only value with bit 8 set. The remaining bytes
should follow immediately. The whole packet must be received within 30mS.
A packet lasting longer than 30mS will be rejected.
There is no minimum packet send rate. If there is no new data, the system will
remain idle.
When the interface unit receives the DATA_REQUEST_LAMP_STATUS
command there is a 2-30mS delay after which the interface will switch to
transmit and output the 5 data bytes in direct succession. After the last byte
has been sent the interface will switch back to receive almost immediately.
Bit 0 - Limit switch error.
Bit 1 - Datum error.
Bit 2 - Lamp type invalid.
Bit 3 - Supply voltage out of tolerance.