User Manual

Copyright 2012 Page 14
4. System Communications
4.1 Basic Communications Format
Standard serial communication is 8 bit data without parity, 1 stop bit in ACSII format.
The lens can also transmit a packed binary format response when requested, using the 8
bit no parity format, to reduce the time taken to transmit data from the lens.
The camera or external unit will initiate all data transfers from the lens except during
Power-Up. At Power-Up, a single automatically generated string is transmitted by the
lens to both channels indicating that a power-up has occurred.
All commands sent to the lens must be in ASCII format and terminate with a
carriage-return character [c/r]. The carriage return character has hex value “0x0D”.
Reply responses from the lens will normally be in ASCII format and terminate with the
character pair, linefeed followed by carriage return [l/f][c/r]. The linefeed carriage
return pair have hex values “0x0A” and “0x0D”.
The packed binary format also has termination character pair “0x0A” and “0x0D”
and neither of these characters will appear within the data string. All data string
characters have either bit 7, or bit 6, or both, set to 1.
4.2 Communicating with an/I Lens
Cooke 5I Prime lenses, Cooke S4I Prime and Zoom lenses have two
communications channels and Cooke PanchroI Prime lenses and RED Zoom lenses
have one communication channel.
Power inputs on the communication channels are monitored at startup and during
operation to determine which channel has control. Lenses that have a single
communication channel will be controlled by the camera interface. For 5I Prime
lenses, the two channels function independently and can both receive commands and
send replies at different baud rates. The two channels on S4I Prime and Zoom lenses,
however, do not function independently. For S4I lenses, if power is present on the
external interface, then the external interface is granted control. If power is not present
on the external interface, then the camera is granted control. S4I lenses can receive
commands on only one channel, but responses will be sent out on both channels.