Experimental Physics and
Industrial Control System

Noboru Yamamoto <[email protected]> · Sat, 20 Nov 1999 09:04:54 +0900

Hi,

Yesterday, I checked UDP broadcast messages on the control network.
Analyzing the packet data, I found some programs were searching for the
channel with the name " " (space character). One of source of
these packet was a process running medm2.4.10 on HP-UX workstation.

 In the source code of medm, I found the following code segment 
in medm/medm/medmCA.c file.  
==================================================================
    if (strlen(name) > (size_t)0) {
        status = ca_build_and_connect(name,TYPENOTCONN,0,
          &(pCh->chid),NULL,medmConnectEventCb,pCh);
    } else {
        status = ca_build_and_connect(" ",TYPENOTCONN,0,
          &(pCh->chid),NULL,medmConnectEventCb,pCh);
    }
==================================================================
This code segment is a part of the body of "int caAdd(char *name, Record
*pr)" function. I checked several versions of medm (2.3.x, 2.4.x, and
dm2k), and found same code segment in all of them.

If you don't have the channel which has " " as its name , medm
keeps sending CA search while it running.

Easiest workaround is to prepare the channel whose name is " ".
(CA Library and dbLoadXXX accepts it.)

Thanks for listening.

Noboru

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System