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The ASYN Facility for Drivers and Device Support

asyn provides a standard mechanism for higher level EPICS software such as device support and 
State Notation Language Programs to communicate with device-specific drivers. Facilities provided 
include connection management, threads for asynchronous devices, trace/debugging control,standard 
interfaces and generic device support.

While "asyn" began as an effort to unify the support for "asynchronous" devices (such as RS-232, 
IEEE-488, and Ethernet sockets), it has recently been extended to be equally useful for synchronous 
devices,such as VME or PCI register-based instruments.

The "synApps" software widely used for synchrotron beamline control and data acquisition
is being converted to use asyn.

The benefits we have realized include:
- Significant reduction in the number of source files and lines of code
- Better trace and debugging control
- Large increase in the number of supported devices, since RS-232, GPIB and Ethernet devices 
  are now all equivalent.
- Code which used to be device-specific (for example fast feedback with the EPID record) is now 
  device independent, provided only that a driver which implements the standard asyn interfaces is 

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