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VME in CMS

              

 


1 Introduction
2 VME64x in CMS
3 VMEBridges
    3.1 CAEN
        3.1.1 Technical Info
        3.1.2 Status
        3.1.3 Software
        3.1.4 Firmware
        3.1.5 Measurements
    3.2 SBS

CAEN VME Bridges

Introduction

CAEN offers two different versions of their VME bridge. One with an optical link, and a second with a USB interface:

  • The CAEN optical bridge. It consists of following modules:
    • A2718 : The VME Controller.
    • A2818 : The PCI card.
  • The CAEN USB bridge (ref. No. A1718). This module is software compatible with the optical version, but needs a different driver.

Link to the CAEN pages: http://www.caen.it/nuclear/product.php?mod=V2718

Some technical information:

  • The VME controllers of the optical version can be chained (i.e. one PCI interface can control several crates which are connected by and optical link in a ring topology.)
  • The maximal length of the fiber is specified by the producer of the optical link components to be 275m for a fiber of type 62.5/125um. (This is the fiber type which comes with the module from CAEN). When you use the fiber type 50/125um the link producer claims that the maximal link length is 550m. Attention: Both maximal lengthes have not been tested by anybody so far.
  • The PCI board A2818 supports 3V and 5V slots PC slots. Attention: There is a jumper on the card which must be set correctly!
  • The software consists of a drivers (specific for the optical or the USB version) and of a user library which is identical for both versions. This means that the user code which works with one module automatically also works with the other version. An exception to this might be software which need a handling of interrupts. Since the USB technology is not adequate for real time applications, interrupt handling in the USB version of the VME bridge is reduced to a simple polling mechanism: The user has to poll the controller if on the VME side an interrupt has occured.
  • The optical version supports full interrupt handling which means that VME interrupts are routed through the bridge and generate an interrupt on the PCI bus. How in detail this interrupt is handled by the software is described in the section "Status".

last changed: 2006-11-16 comments to: Christoph Schwick