asynDriver: Asynchronous Driver Support - Known Problems

March 30, 2005

Release 4-2


Device support is not returning 2 (do not convert) for ai records when it should. This means that the VAL field is being set back to 0 by the record after device support writes to it.


The record sometimes does not read the current input and output EOS values from the driver when it connects.

Release 4-1


If read reads maxchars, it forces the last character to be 0 and returns asynOverflow if it wasn't.

drvAsynSerialPort,drvAsynIPPort - Error reporting

These do not properly set an error message in asynUser.errorMessage when they return asynError.


This calls setOption for clocal. This only works on vxWorks because vxWorks uses the name CLOCAL for what POSIX calls CRTSCTS.


If a call to a low level driver, which registered itself as canBlock, completes without blocking then the asynchronous completion may never occur. This will be fixed in the next release.

drvAsynIPPort and drvAsynSerialPort

The problem reported for version 4 about segmentation faults on cygwin-x86 has been fixed.

Release 4-0


asynRecord (and other code) use epicsStrSnPrintEscaped. In EPICS 3.14.6 the files epicsVsnprintf on vxWorks (which gets called by several other epicsXXXprintf routines) and epicsStrSnPrintEscaped each have a bug could cause buffer overflow. These bugs are guaranteed to lead to corruption in asynRecord if the received string is longer than 40 characters.




Release 3-3


If vxiName is specified as "inst" then the driver incorrectly says that it does not block.


If asynRecord is attached to a port that does not implement asynOctet, then asynRecord crashes of it attempt to send/receive a message.


The next release gaurantees that when queueRequest is called:

  1. Exactly one of the following occurs:
  2. If either the queue or timeout callback is active when cancelRequest is called, it will not return until the callback completes.

Release 3-2

Mac OS X (Darwin)

The RPC library on Mac OS X 10.3.3 does not handle device timeouts properly and may cause core dumps. A bug report has been filed with Apple. A workaround is to use the GNU glibc RPC/XDR routines.


Attempting to change the trace file to "stdout" does not work becuase vxWorks has per-task standard output streams.

Release 3-1

EPICS Base R3.14.6

When building with EPICS Base R3.14.6 or greater, comment out the epicsInterruptibleSyscall.h and epicsInterruptibleSyscall.c lines in asyn/Makefile:

@@ -19,10 +19,10 @@
 SRC_DIRS += $(ASYN)/asynDriver
 INC += asynDriver.h
 INC += epicsInterruptibleSyscall.h
-INC += epicsString1.h
+#INC += epicsString1.h
 asyn_SRCS += asynManager.c
 asyn_SRCS += epicsInterruptibleSyscall.c
-asyn_SRCS += epicsString1.c
+#asyn_SRCS += epicsString1.c
 SRC_DIRS += $(ASYN)/asynGpib
 INC += asynGpibDriver.h

Mac OS X (Darwin)

The RPC library on Mac OSD 10.3.3 does not handle device timeouts properly and may cause core dumps. A bug report has been filed with Apple. A workaround is to use the GNU glibc RPC/XDR routines.

Interrupt Callback

If a user callback calls a low level driver with an infinite or very long timeout, there is no way to make the call terminate. Is there a generic way to abort the call?

Greensprings IP488

Does not support GPIB specific functions.

NI1014 VME Gpib driver

This needs to be implemented for asynDriver.

Generic EPICS device support

Think about creating generic support for connecting to EPICS records.

Network Protocols

Consider generic support for various network protocals: Modbus, etherIP, etc.