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computer, the information in Figure 3-7 can be used when in-
terpreting data and error conditions.
Bit six is the SRQ bit. If this bit is set the service request was
made by the Model 706. Bit five determines the meaning of
bits zero through three. If bit five is set, the error conditions
listed in Table 3-9 apply to bits zero through three. If bit five is
cleared, the data condition listed in the table apply.
To output the status byte in binary form (Figure 3-7) enter the
following
program into the HP-85.
PROGRAM
COMMENTS
10 REMOTE 718 (END LINE)
Programs the Model 706
2d S = SPOLL (718) (END
into the remote mode.
Start serial poll sequence.
LINE)
30 DISP "B7 B6 85 B4 B3
Display contents of
82 Bl BO" (END LINE)
quotation mark.
40 FOR I =7 to 0 STEP -1
Loop eight times.
(END LINE)
-
50 DISP BIT (S,I); (END
Display status byte.
LINE)
60 NEXT I (END LINE)
70 DISP (END LINE)
80 END (END LINE)
Press the RUN key to start the program. After the RUN key is
pressed the Model 706 outputs the status byte to the con-
troller. The controller then displays the
status
byte in the form
shown in Figure 3-7.
l-NO
REMOTE
1
I
I
I
I
I
I
I
87
B6
B6
B4
83
82
El
B6
l/O
110
l/O
110
l/O
110
l/O
_I 110
I
I
1
I
L
-
1
O:;N:=
Sl3lUNG
TIME
O= END OF
INTERVAL
TIME
J
O-END
OF
SCAN
O-TIMER
ALARM
Figure 3-7. Status Byte Format
3.7 STATUS-WORD
(U)
The status word command allow access to information con-
cerning various operating modes of the Model 706. The
status word also contains information
about the present
status of the input and output lines on the digital I/O port.
When the correct command is given, the Model 706 outputs
the status word or I/O status the next time it is addressed to
talk instead of sending its normal data string. Each byte in the
status word is a number corresponding
the previously pro-
grammed parameter with the following sequence:
706 ADEJKPTGMY
Refer to Figure 3-8 for an example of the status word.
To output the status word enter the following program into
the HP-85.
PROGRAM
COMMENTS
10 REMOTE 718 (END LINE)
Programs the Model 706
into the remote mode.
20 CLEAR 7 (END LINE)
30 OUTPUT 718; "U4X"
(END LINE)
Clears the Model 706.
Outputs status word.
40 ENTER 718; A$ (END
LINE)
Obtains data string.
50 DISP A$ (END LINE)
Displays data string.
60 END (END LINE)
End of oroaram.
Press the RUN key to implement the program. After pressing
the RUN key the Model 706 outputs the status word. In this
case the status word is transmitted to the controller with a
prefix.
NOTES
Figure 3-8. Status Word Format
1. SRQ status information contains three bytes. These three
bytes assume the decimal value previously set by the SRQ
mode command.
2. To make sure proper status is returned, the status word
should be read immediately after sending the command.
Otherwise, instrument status may be changed from the
front panel, resulting in erroneous status information.
3. The status word should not be confused with the SRQ
status byte. The status word contains a number of bytes
pertaining to the various operating modes of the instru-
ment. The status byte is a single byte that is read by using
the serial poll sequence and contains information on SRQ
status and error or data conditions.
3-28
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