Optimizing
Programs
Note
Block Data Transfers
HP VISA
ViSession defaultRM, id;
//open device (VISA) session to the HP E1563 viOpenDefaultRM (&defaultRM);
viOpen (defaultRM, “VXI0::24::INSTR”,VI_NULL,VI_NULL, &id);
SICL
INST id;
//open device (SICL) session to the HP E1563 id = iopen(“vxi,24”)
Or, to open an interface session to the HP E8491A:
INST id;
//open (SICL) session to the VXI interface id = iopen(“vxi”)
The HP E8491A IEEE 1394 interconnect uses the interface name VXI (or vxi). The interface number is assigned using the ‘I_O Config’ utility (Chapter 2). In the examples above, the logical address of the HP E1563 digitizer is 24 and INSTR indicates a VISA instrument control resource.
Programs that run over the IEEE 1394 serial bus are optimized by transferring data between the PC and the instrument in blocks. The following section identifies HP VISA and SICL functions that perform block transfers.
Refer to “Chapter 4: IEEE 1394 Fundamentals and Interface Overview” for detailed information on data transfers using the IEEE 1394 data transfer protocol.
VXIplug&play drivers for selected instruments contain functions that perform block transfers. You will need to consult the driver help file to determine if the driver for a particular instrument supports block transfers.
The following HP VISA functions perform block transfers over the IEEE 1394 serial bus:
viMoveIn8 | viMoveOut8 | viMove |
viMoveIn16 | viMoveOut16 | viMoveAsync |
viMoveIn32 | viMoveOut32 |
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36 VXI Programming Using the IEEE 1394 Serial Bus |