Experimental Physics and
Industrial Control System

"Szalata, Zenon M." <[email protected]> · Sat, 15 Sep 2007 19:01:21 -0700

I have simple softIOC which reads values from a HP34401A multimeter.  The multimeter is connected via GPIB bus to NI PCI-GPIB interface.  The IOC is built with EPICS 3.14.9, ASYN 4-8, and linux-gpib 3.2.09.

The command which reads the value is:

 {&DSET_LI,GPIBREAD,IB_Q_HIGH,"READ?","%f",0,80,NULL,0,0,NULL,NULL,NULL},

Caget shows something like: 1091779303, which is nonsence.  The value should be about 9.202.  When I change the record to stringi, then I see correct 9.2 type value.  Also in edm I see the same 1091779303 unreal number.  When I display it in hex, I see 0x41133AE7.
I also wrote a simple c program where:
  int v=0x41133ae7;
  float f;
  memdpy( &f,&v,sizeof(int));
  print( "0x%x %f\n",v,f);

This gives an output:
0x41133ae7 9.201880

All of this is on RHEL4 linux.  It seems to me that EPICS is interpreting the byte order in a way different than the c program.  But then what do I need to do to have the PV floating value be correct?  Thanks in advance,
Zen

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System