Epics Tips And Tricks Multiple IOCs

multiple IOCs

newest (2015/06) tech-talk knowledge

$ https://epics-controls.org/tech-talk/2015/msg00897.php :
https://wiki-ext.aps.anl.gov/epics/index.php/How_to_Make_Channel_Access_Reach_Multiple_Soft_IOCs_on_a_Linux_Host or https://wiki-ext.aps.anl.gov/epics/index.php/How_to_Configure_Channel_Access or https://epics-controls.org/base/R3-14/12-docs/CAref.html describe the basic issue of reaching multiple IOCs running on the same computer --> Need to use broadcast address.
For the command line 'caget' you need to set the EPICS_CA_AUTO_ADDR_LIST and EPICS_CA_ADDR_LIST environment variables. For CSS, you need to set the corresponding preferences. In the UI, that's under Edit/Preferences/CSS Core/EPICS for the running instance, or better use a "plugin customization" file as described in the "Hierarchical Preferences" section of the CSS book, http://cs-studio.sourceforge.net/docbook/css_book.pdf. The related setting would be
## File "my_settings.ini" org.csstudio.platform.libs.epics/auto_addr_list=false org.csstudio.platform.libs.epics/use_pure_java=true org.csstudio.platform.libs.epics/addr_list=xx.xx.19.255 127.0.0.1 org.csstudio.platform.libs.epics/max_array_bytes=100000000
.. and then you run css like this:
css -pluginCustomization /full/path/to/my_settings.ini

To have one PC / Computer per IOC/Server seems to be an annoying situation.
Solution would be to be able to have several IOCs running on a PC. But you will be faced by the following Problems
(taken from talk of Kenneth Evans: "_Channel Access in Depth_", Kenneth Evans, Jr., March 8, 2005 as Part of the EPICS “Getting Started” Lecture Series, p15):

Solution 1: EPICS_CA_ADDR_LIST

EPICS_CA_ADDR_LIST
• Determines where to search
• Is a list (separated by spaces)
  • “123.45.1.255 123.45.2.14 123.45.2.108”
• Default is broadcast addresses of all interfaces on the host
  • Works when servers are on same subnet as clients
• Broadcast address
  • Goes to all servers on a subnet
  • Example: 123.45.1.255
  • Use ifconfig –a on UNIX to find it (or ask an administrator)

By setting the EPICS_CA_ADDR_LIST, the EPICS Channel Access (Client) Address List on the client site.
E.g. for MEDM:

1. export EPICS_CA_ADDR_LIST and start medm in the same session
   $> export EPICS_CA_ADDR_LIST && medm &

Solution 2: make use of more EPICS environment variables to allow inter IOC communication

Following the thread in tech-talk Multiple IOC from 2007:

   It was fixed by setting the CAS Beacon Address List to the address and ports of the other IOC's CA repeater port.

   IOC1

   EPICS_CAS_BEACON_ADDR_LIST=nnn.nnn.nnn.nnn:5071
   EPICS_CA_ADDR_LIST=nnn.nnn.nnn.nnn:5070

   IOC2

   EPICS_CA_Server_Port=5070
   EPICS_CAS_Server_Port=5070
   EPICS_CA_Repeater_Port=5071
   EPICS_CAS_BEACON_ADDR_LIST=nnn.nnn.nnn.nnn:5065
   EPICS_CA_ADDR_LIST=nnn.nnn.nnn.nnn:5064