Re: Re: write a CA client by API in Eclipse

[肖麟阁 via Tech-talk <tech-talk@aps.anl.gov>]

Hi,

    i have tried for many times. i found that the useful libs are not libca.so and libCom.so. i can't work well with the two libs(because it shows that it can't find the lib,even if the libs exist). then i found that the actual libs are "libca.so.3.15.6" and "libCom.so.3.15.6".when i add them to the directory it can build and work well.

    when the program is running, the console shows:

    ---

    searching ...
**** The executable "caRepeater" couldn't be located
**** because of errno = "No such file or directory".
**** You may need to modify your PATH environment variable.
**** Unable to start "CA Repeater" process.
some channels not found yet
reading ...
some values not received
Beam current (not found): 6.95269e-310
Gap          (not found): 2.0737e-317

    ---

    i don't find some documents about the caRepeater. i don't konw if i can ignore the error.

-----原始邮件-----
发件人:"Johnson, Andrew N." <anj@anl.gov>
发送时间:2019-10-01 00:18:18 (星期二)
收件人: "肖麟阁" <xiaolg@ihep.ac.cn>, "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
抄送:
主题: Re: write a CA client by API in Eclipse

Hi,

On 9/30/19 7:33 AM, 肖麟阁 via Tech-talk wrote:

I try to run it, but errors come out like following:

        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:43: undefined reference to `ca_task_initialize'
        makefile:29: recipe for target 'testEPICS' failed
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:46: undefined reference to `ca_search_and_connect'
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:50: undefined reference to `ca_search_and_connect'
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:55: undefined reference to `ca_pend_io'
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:88: undefined reference to `ca_message'
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:113: undefined reference to `ca_array_get'
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:117: undefined reference to `ca_array_get'
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:122: undefined reference to `ca_pend_io'
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:144: undefined reference to `ca_message'
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:157: undefined reference to `ca_state'
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:165: undefined reference to `ca_state'
        /home/xlg/eclipse-workspace/testEPICS/Debug/../main.c:169: undefined reference to `ca_task_exit'
        collect2: error: ld returned 1 exit status
        make: *** [testEPICS] Error 1
        "make all" terminated with exit code 2. Build might be incomplete.        

Those error messages are from the linker, you need to tell it to link your program with the two libraries, so assuming you're using your own build script the linker needs the additional parameters '-lCa -lCom' and it might need others telling it where to find those libraries such as '-L/path/to/your/library/directory'

    by the way, someone else tell me that i just need libCa.so, libCom and some .h files to write a CA Client. is that true?

That is true. The EPICS build system provides a common framework that was designed to make building client programs easier, but you are not required to use it.

- Andrew

-- 
Complexity comes for free, Simplicity you have to work for.