National Instruments NI-VXI

Chapter 2 Introduction to the NI-VXI Functions

15 NI-VXI User Manual

timeout = 2000L; /* 2 seconds */

/* Notice the use of the macros for defining the access */

/* parameters. These can be found in the NI-VXI header files */

addrptr1 = (UINT32) MapVXIAddress(AccessP_Space(A16_SPACE) |

AccessP_Priv(NonPriv_DATA) |

AccessP_BO(MOTOROLA_ORDER) |

AccessP_Owner(0),

addr, timeout, &window1, &ret);

if (ret >= 0) /** MapVXIAddress call is successful **/

{/* The following code reads the ID register of a device */

/* at logical address 10. */

la = 10;

addrptr = (UINT16 *)((UINT32) addrptr1 + 64 * la);

VXIpeek(addrptr,2, &svalue));

if (BusErrorRecv)

printf("Bus Error has occurred.\n");

else printf("Value read was %hd.\n", svalue));

ret = UnMapVXIAddress(window1);

} else printf("Unable to access window.\n");

/* Close library when done */

ret = CloseVXIlibrary();

}

Notice that the return variable for the MapVXIAddress() function is a

pointer. While you can dereference this pointer directly on some

platforms, we recommend that you use the VXIpeek() and

VXIpoke() macros and functions in NI-VXI instead.

You can define BINARY_COMPATIBLE when compiling your program

to force NI-VXI to use a version of VXIpeek() and VXIpoke()

macros that will work on all embedded and MXI platforms. In addition,

you can use the functions, rather than the macros, to ensure future

compatibility. To force the compiler to use the functions, put the

function name in parentheses, for example,

(VXIpoke) (addrptr, 2, 0);

instead of

VXIpoke (addrptr, 2, 0);