Bonn Shutters

The Firmware

All shutter operation is performed by the microcontroller firmware.


After power on or shutter reset (Reset button) the blades are moved for position calibration. Then the firmware starts polling the "shutter open/close" signal.

Blade movement

The shutter blade movements during open or close follow a trapezoidal velocity profile which is identical for both blades and both movement directions. It is characterized by 3 parameters: Acceleration, maximum velocity and blade travel distance.

ShCU commands

For diagnostic, monitoring or parameter modification purposes a number of commands allow to communicate with the ShCU via the RS232 connection. All commands consist of two lower case command characters and numerical parameters separated by blank spaces. Each command sends its answer value (if defined) plus the prompt "c>".

For illustration a command sequence is shown which we recommend to apply after unpacking a new shutter to familiarize with the device and its control.

ia 1 Switch to interactive mode: Answer prompts will be preceeded by a line break.
s? Shows a list of all standard commands with a one line description.
s! Shows a list of all special commands with a one line description.
os Opens the shutter. If opened by command the shutter can not be closed by the push button or external signals! Therefore ...
cs ... closes the shutter.
sh 0 Shows an explanatory list of the velocity profile parameters for blade A plus parameters of the reset procedure.
sh 1 The same for blade B.
pp Get a 1 line list of parameters (for host communication).
ex 100 Perform a 100msec exposure operation.
ss Tells you which blade is in the shutter aperture.
ex 10 Perform a 10msec exposure operation.
ss Tells you that now the other blade is in the shutter aperture.
ac 25000 This will redefine the acceleration parameter. To make it active do a reset (for lower acceleration values the calculation of the velocity profile and thus the reset takes longer)...
rs ... while the reset is going on type ...
sv 1 ... check status byte #1 and look for the "S_blade_A_offline" and the "S_blade_B_offline" status bits. Repeat the command to see how things change.
ex 100 Perform a 100msec exposure operation and check for the "rubberband" effect that is due to the trapezoidal velocity profile. The low acceleration makes it recognisable.
sh 0 Check the current parameters (in particular the acceleration).
fd Reset all parameters to their factory default values. To make it active do a reset...
rs Wait until the blades have reached their destination. Then try on your own.