2CAN：Controller Area Network Controller Area Network (CAN) is a broadcast, differential serial bus standard, originally developed in the 1980s by Robert Bosch GmbH, for connecting electronic control units (ECUs).CAN was specifically designed to be robust in electromagnetically noisy environments and can utilize a differential balanced line like RS-485.It can be even more robust against noise if twisted pair wire is used. Although initially created for automotive purposes (as a vehicle bus), nowadays it is used in many embedded control applications (e.g., industrial) that may be subject to noise.Bit rates up to 1 Mbit/s are possible at network lengths below 40 m. Decreasing the bit rate allows longer network distances (e.g. 125 kbit/s at 500 m).The CAN data link layer protocol is standardized in ISO (2003).This standard describes mainly the data link layer — composed of the Logical Link Control (LLC) sublayer and the Media Access Control (MAC) sublayer — and some aspects of the physical layer of the OSI Reference Model.All the other protocol layers are left to the network designer's choice.
7NI PCI-CAN/2 Operationg System Windows 2000/NT/XP/Me/98 LabVIEW Real-TimeRecommended SoftwareLabVEIWLab Windows/CVIOther Compatible SoftwareC/C++Visual Basic 6Application Software (included)Bus monitor utilityDriver Software (included)NI-CAN
8ESD CAN-CBX-AI814 ・CANopen module with In-Rail-Bus ・8 A/D-converter inputs・resolution 14 bit・input voltage range・CANopen
9Monitoring system for the HCAL prototype LED monitoring systemSystem conceptChoice of LEDTest of fiber bundle- LED driver studiesTemperature monitoringSlow control
10Slow ControlTo intervene on detector parameters frontend processors (mostly VME) and interfaces can be addressed via a dedicated slow control bus connected to the monitoring workstation.As bus systems two options are considered at present:CANbus is a standard slow control bus which is widely used in the VME sector.It also offers accessibility to crates and power supplies allowing additional monitoring and maintenance possibilities.Ethernet as slow control bus is an inexpensive alternative.Most VME CPUs are equipped with standard ethernet interfaces.The protocol is more flexible and allows a higher bandwidth then CANbus.To avoid problems this net should be separated from the CERN wide networkThe slow control processors perform e.g. voltage and temperature checks, set voltages and thresholds.