Recently we revamped a vapour phase epitaxy reactor. In the old configuration there was a SBC MM70 from Mentec running a application program under RSX11-M. Each of the I/O cards has 8 differential analog inputs, 8 analog differential outputs and 32 digital input/outputs. In the new configuration a new controller board communicates via an isolated RS-485 line with a PC running a Labwindows program and controls the four I/O cards with the help of a simplified Q-Bus rack ( no DMA, no interrupts, no ... ).
 
Reading an input or writing to an output port is done in 40 µsec, fast enough for this application.
 
I think we can find a solution if you want to extend the life of an installation with (slow) Q-Bus cards, keeping often all the external cabinet cabling and if you are willing to develop a new control program on a PC.
 
 
 
 
 
 
 

old and new controller :

the old rack had a lot of serial ports for communication with temperature controllers etc
 
 

new controller board with a simplified Q-Bus back panel
 
 

some views of the installation

the new rack is situated at the left, just beneath the old PDP-11 rack ventilator
 
 


reactor chamber ( during modification )
 
 


80 valves and some flow controllers
 
 


on the top : rack with isolation and distribution cards, with a lot of outside connectors
on the bottom : new rack with RS-485 communication line to a PC
 
 


example of computer screen
 
 

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