Experimental Physics and
Industrial Control System

"Mark Rivers" <[email protected]> · Sat, 19 Dec 2009 08:39:06 -0600

Folks,

We found a problem with CAJ and the PV gateway yesterday.  The problem is that CAJ "out of the box" (e.g. without changing any of the default properties) will connect fine to PVs on the local subnet if they are contained in a VME IOC or soft IOC.  But CAJ will not connect to PVs that are present in a PV gateway on the local subnet.

We've figured out the problem, and it is easy to reproduce even with traditional CA from EPICS base.  The problem is that CAJ defaults to a broadcast address of 255.255.255.255 when searching for PVs.  VME IOCs and soft IOCs respond to such a broadcast, but the PV gateway does not.

Here is the proof using only the cainfo program that comes with EPICS base.  13IDC:m1 is a PV in a VME IOC.  XFD:srCurrent is a PV in a PV gateway.  If we use the default settings in CA cainfo connects to both PVs fine.
corvette:Ametek/AmetekApp/src>unsetenv EPICS_CA_ADDR_LIST
corvette:Ametek/AmetekApp/src>unsetenv EPICS_CA_AUTO_ADDR_LIST
corvette:Ametek/AmetekApp/src>cainfo 13IDC:m1
13IDC:m1
    State:         connected
    Host:          ioc13idc.cars.aps.anl.gov:5064
    Access:        read, write
    Data type:     DBR_DOUBLE (native: DBF_DOUBLE)
    Element count: 1
corvette:Ametek/AmetekApp/src>cainfo XFD:srCurrent
XFD:srCurrent
    State:         connected
    Host:          geopv-gw.cars.aps.anl.gov:5064
    Access:        read, no write
    Data type:     DBR_DOUBLE (native: DBF_DOUBLE)
    Element count: 1

However, if we set the EPICS_CA_ADDR_LIST to 255.255.255.255 then cainfo connects to the VME IOC fine, but does not connect to the PV gateway PV. 

corvette:Ametek/AmetekApp/src>setenv EPICS_CA_AUTO_ADDR_LIST NO
corvette:Ametek/AmetekApp/src>setenv EPICS_CA_ADDR_LIST 255.255.255.255
corvette:Ametek/AmetekApp/src>cainfo 13IDC:m1
13IDC:m1
    State:         connected
    Host:          ioc13idc.cars.aps.anl.gov:5064
    Access:        read, write
    Data type:     DBR_DOUBLE (native: DBF_DOUBLE)
    Element count: 1
corvette:Ametek/AmetekApp/src>cainfo XFD:srCurrent
Channel connect timed out: 'XFD:srCurrent' not found.
XFD:srCurrent
    State:         never connected
    Host:          <disconnected>
    Access:        no read, no write
    Data type:     DBR_invalid (native: TYPENOTCONN)
    Element count: 0

Because of this CAJ will not find PVs in PV gateways unless the CAJ properties are changed. Is this a bug in the PV gateway, or just a limitation of the default broadcast address of CAJ?

Thanks,

Mark

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System