User manual

Chapter 6 Backplane Programming
6-5
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Read Status Data Format
The four figures below show the format of read status data. Because a 1700’s block transfer
read length is fixed, the format of the data is based on the module you are using. A 1731 or
1741 can transmit only one parameter value at a time. A 1732 or 1742 can transmit up to three
parameters while the remaining modules can transmit a maximum of five parameters at a time.
hýAll 1700 module set bit 7 of the status
word while in read status mode. The
module resets this bit when transmitting
position and tachometer data. Use this
bit to determine the mode of operation.
hýIf you enter read status mode and do not
request any parameters, the module
sends 000h in the echo and parameter
value words.
hýWhen using a 1731, 1741, 1732, or 1742,
you can request more parameter values
than the module can transmit back. If you
do this, the module will respond with an
error code in the status word.
hýThe first word of read status data is an
echo of the last read status instruction
accepted by the module. See table 6.3
on the following page for the format of
the read status instructions.
hýParameters are read from the module by
channel. For example, you cannot read
the scale factor of channels one and two
at the same time.
hýThe precedence order of the parameter
values is:
Scale Factor
Circular Offset
Linear Offset
Preset Value
Tachometer Response
hýParameter values are transmitted in BCD
format. The tachometer response value
uses the same format it is programmed
with. Its range is zero to four.
hýYou can still program the module while
it is in read status mode. However, you
must issue a read status instruction to
read the new value once a parameter is
changed.
1734 / 1744
Word 1
Echo of last Read Status Instruction
Word 2
Word 3
Word 4
Word 5
Word 6
Word 7
Word 8
Word 9
First requested parameter value
Second requested parameter value
Third requested parameter value
Fourth requested parameter value
Fifth requested parameter value
Not Used, Set equal to 0000h
Status Word
Not Used, Set equal to 0000h
1733 / 1743
Word 1
Echo of last Read Status Instruction
Word 2
Word 3
Word 4
Word 5
Word 6
Word 7
First requested parameter value
Second requested parameter value
Third requested parameter value
Fourth requested parameter value
Fifth requested parameter value
Status Word
1732 / 1742
Word 1
Echo of last Read Status Instruction
Word 2
Word 3
Word 4
Word 5
First requested parameter value
Second requested parameter value
Third requested parameter value
Status Word
1731 / 1741
Word 1
Echo of last Read Status Instruction
Word 2
Word 3
Requested parameter value
Status Word
Figure 6.2 Read Status Data Format