Shutter Control Unit
The ShutterCU provides high precision control of the shutter blade movement. Software command and hardware signal interfaces exist to connect the system to the camera and/or instrument control H/W and S/W.
The Interface to the camera/instrument control system is based on hardware control lines. Software command communication is also possible (ASCII over RS232, see below).
Hardware control lines
Three lines exist (i) for shutter open/close operation, (ii) to indicate the "shutter closed" status and (iii) any error condition. These lines are accessible through the SubD9 connector labelled "Control". Use of the status and error control lines is optional.
Serial command line (use is optional)
Through the RS232 line (SubD9 connector labelled "RS232") a host can take control to get status information, to recover from error conditions and to redefine velocity profile parameters. Commands exist of 2 ASCII characters and up to 3 parameters (e.g. "ex 1000" for a 1000msec exposure).
The exposure start signal (falling edge) is continously polled by software. The polling loop takes about 25µsec. This time delay sets the ultimate limit for the shortest possible exposure. In addition the shortest possible exposure puls is limited electronically to 300µsec.
The shutter can be operated in various ways
- Manually: Press/release the open button to open/close the shutter.
- TTL compatible signal: Falling edge opens, rising edge closes the shutter. Input is via the connector labelled "Control".
- By command: Send the "ex" command over the RS232 serial line to initiate a shutter operation (exposure time in msec). This is thought to be used for testing and demonstration.
[top of page]