iSys C to V - Manual (Page 7)

PAGE 7 --- C to V User Guide © iSys-The Imaging Systems Group Inc.
where XX = high byte of the number of bytes/scan
YY = low byte of the number of bytes/scan
Example:
To send a plot that is rastered to 200 bytes/scan, send the following 6 byte
header before each and every scan of 200 bytes:
1B 2A 72 00 C8 01
00C8 hex = 200 decimal
for a plot consisting of 1728 bytes/scan, send
1B 2A 72 06 C0 01
06C0 hex = 1728 decimal
2.3 - Enhanced Transfer Format with Run Length Encoding (RLE)
This transfer format allows raster data to be run length encoded for smaller file storage size and higher effective interface
throughput. The format of the 6 byte header is:
1B 2A 72 XX YY 02
where XX = high byte of the number of bytes/scan
YY = low byte of the number of bytes/scan
Once the scan header is sent, the raster data must be sent using the following format:
byte1, byte2, byte1, byte2...
where byte1 = run length number of similar bytes: 01H <= byte1 <=FFH
byte2 = raster byte value
the sum total of all byte1 values in a given scan must equal the XX, YY value sent in the 6 byte scan header.
Example:
1B 2A 72 00 C8 02
00C8 hex = 200 decimal
then
03 FA, 29 31, 9C 0F
(03 + 29 + 9C = C8 hex or 200 decimal)
This would be a complete and valid scan.
NOTE:
Scans can be inter-mixed in any combination between (2.2) and (2.3) above. This allows scans that can be efficiently compressed
to be sent using (3), while scans that do not run length compress efficiently can be sent using (2). This will help maximize total file
compression.