Experimental Physics and
Industrial Control System

Our IOCs are now all running base 7.0.5.  We see an issue with medm screens containing string files using PVs that end in a “$”.  We can only change the first character in the string.

 

This is easy to reproduce using the caput and cainfo clients from base 7.0.5 to a PV in an IOC running base 7.0.5.

 

cainfo without the $ modifier shows the field is a DBF_STRING.

 

corvette:local/epics-devel/base-7.0.6>/usr/local/epics-devel/base-7.0.5/bin/linux-x86_64/cainfo 13BMD:userTran20.CLCA

13BMD:userTran20.CLCA

    State:            connected

    Host:             ioc13bmd.cars.aps.anl.gov:5064

    Access:           read, write

    Native data type: DBF_STRING

    Request type:     DBR_STRING

    Element count:    1

 

cainfo with the $ modifier shows the field is a DBF_CHAR of size 120

 

corvette:local/epics-devel/base-7.0.6>/usr/local/epics-devel/base-7.0.5/bin/linux-x86_64/cainfo 13BMD:userTran20.CLCA$

13BMD:userTran20.CLCA$

    State:            connected

    Host:             ioc13bmd.cars.aps.anl.gov:5064

    Access:           read, write

    Native data type: DBF_CHAR

    Request type:     DBR_CHAR

    Element count:    120

 

A caput without the $ modifier works, but that would be limited to 40 characters.

 

corvette:local/epics-devel/base-7.0.6>/usr/local/epics-devel/base-7.0.5/bin/linux-x86_64/caput 13BMD:userTran20.CLCA "A+B"

Old : 13BMD:userTran20.CLCA

New : 13BMD:userTran20.CLCA          A+B

 

A caput with the $ modifier does not work, only the first character in the string was changed.  It should have changed from A+B to B+A, but instead it changed to B+B.

 

corvette:local/epics-devel/base-7.0.6>/usr/local/epics-devel/base-7.0.5/bin/linux-x86_64/caput -S 13BMD:userTran20.CLCA$ "B+A"

Old : 13BMD:userTran20.CLCA$ A+B

New : 13BMD:userTran20.CLCA$ B+B

 

I see the same issue when writing to the DESC field of an ao record.

 

corvette:local/epics-devel/base-7.0.6>/usr/local/epics-devel/base-7.0.5/bin/linux-x86_64/caput testAo_1.DESC "123"

Old : testAo_1.DESC                  H23

New : testAo_1.DESC                  123

 

When writing with the $ modifier it should have changed “123” to “321”, but instead it is “323”.

 

corvette:local/epics-devel/base-7.0.6>/usr/local/epics-devel/base-7.0.5/bin/linux-x86_64/caput -S testAo_1.DESC$ "321"

Old : testAo_1.DESC$ 123

New : testAo_1.DESC$ 323

 

Is this a bug, or am I misunderstanding how long strings are supposed to work?

 

This looks similar to this bug that is fixed in 7.0.6.1, but that says it was specific to the CALC field.  https://github.com/epics-base/epics-base/issues/194

 

Thanks,

Mark