The CANspy module is used in Atlas to monitor and/ or control multiple CAN-buses in the detector control system (DCS). The CANspy allows the user to up to 32 Can buses.For 32 channels special cables are required, for 16 channels standard CAN-cables an be used. It is a single height (1 HE) module. The depth is only 50 mm, so it does not obstruct the airflow in vertically cooled racks. A connection between the spy-port and one of the CAN-buses is selected by means of the control port, which is also a CAN-bus connection. There is no electrical connection between the control-port and the the spy-port or the CAN-buses. There is only a high value resistor to ground on each port to prevent them from floating. The module is a three pole switch with 32 positions. Modules can be interconnected to create a larger switch. The module consumes less than 100 mA from an external power supply of 7.5 V.

front panel

Have a look at the special cables or the system installed in ATLAS. Click the pictures for a larger view. Cable description.
Every CANspy channel handles two buses
The system (3 modules) installed in ATLAS
dual channel
ATLAS rack
The power comes from small plug convertors, mounted in the back of the rack.
The other things you can see is what we call the bobo-screen, a status display of the DCS system. Behind that, the enormous amount of cables for the muon end-cap alignment monitoring.

For the description of hard- and software go to CANspy.pdf
Or go to the Nikhef electronics for Atlas page.

  March 2009, Henk Groenstege