Measurement Computing Personal488 rev.3.0 - Manual (Page 84)

Personal488 for Windows 95/98/Me/NT/2000 04-10-01 API Reference 6-16
EnterX
Syntax LONG WINAPI EnterX(DevHandleT devHandle, LPBYTE data,DWORD
count,BOOL forceAddr,TermT*term,BOOL reserved,LPDWORD
compStat);
devHandle refers to either an IEEE 488 interface or an external device.
data is a pointer to the buffer into which the data is read.
count is the number of characters to read.
forceAddr is used to specify whether the addressing control bytes are to be issued for
each EnterX command.
term is a pointer to a terminator structure that is used to set up the input terminators.
If term is set to 0 , the default terminator is used.
reserved - this value is ignored.
compStat is a pointer to an integer containing completion status information.
Returns -1 if error
otherwise, the actual count of bytes transferred. The memory buffer pointed to by the data
parameter is filled in with the information read from the device. Note that the actual
count does not include terminating characters if term characters are specified by the
term in function. In addition, term characters are not returned but are discarded.
Bus States With interface handle: *ATN, data
With external device handle: ATN
•UNL, MLA, TAG, *ATN, data
Example term.EOI = TRUE;
term.nChar = 1;
term.EightBits = TRUE;
term.termChar[0] = ‘\r’;
bytecount=EnterX(timer,data,1024,0,&term,1,&stat);
See Also OutputX, Term, Buffered
The EnterX command reads data from the I/O adapter. If an external device is specified, then Driver488 is
addressed to Listen, and that device is addressed to Talk. If an interface is specified, then Driver488 must
already be configured to receive data and the external device must be configured to Talk, either as a result
of an immediately preceding
EnterX command or as a result of one of the Send commands. EnterX
terminates reception on either the specified count of bytes transferred, or the specified or default terminator
being detected. Terminator characters, if any, are stripped from the received data before the
EnterX
command returns to the calling application.
The forceAddr flag is used to specify whether the addressing control bytes are to be issued for each
EnterX command. If the device handle refers to an I/O adapter, then forceAddr has no effect and
command bytes are not sent. For an external device, if forceAddr is TRUE then Driver488 always sends
the UNL , MLA , and TAG command bytes. If forceAddr is FALSE , then Driver488 compares the current
device with the previous device that used that interface adapter board for an EnterX command. If they are
the same, then no command bytes are sent. If they are different, then EnterX acts as if the forceAddr
flag were TRUE and sends the command bytes. The forceAddr flag is usually set TRUE for the first
transfer of data from a device, and then set FALSE for additional transfers from the same block of data from
that device.
Additional Enter Functions
Driver488 provides additional
Enter routines that are short-form versions of the EnterX function. The
following Enter functions are already defined in your header file.