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7 Serial Communications
NX-series Communications Interface Units User’s Manual (W540)
7-3 Data Used by the Serial Communications Protocol
7
7-3-2 SIDs and SID Responses
It is necessary to confirm that the input notification data and output notification data that are sent
between the CPU Unit or communications master and CIF Unit are received normally. The following
data is used for that purpose: Input SID and Output SID Response in the input notification data and
Output SID and Input SID Response in the output notification data. The default values for all of these is
00 hex.
The Input SID and Input SID Response are used as des
c
ribed in the following table when the CIF Unit
inputs receive data to the CPU Unit or communications master.
7-3-2 SIDs and SID Responses
Input SID and Input SID Response
Step Process
CPU Unit or communications master
processing
Communi-
cations
dire
ction
*1
CIF Unit processing
1 No data
reception
• The communications master
receives the input notification data
given on the right.
• The Input SID is 00 hex, so the mas-
ter knows that there is no input data
i
n
cluded in the input notification data
that was received.
• The CIF Unit inputs the following input
notification
d
ata.
• The CIF Unit sets the Input SID to 00 hex
to
tell
the CPU Unit or communications
master that no input data is included in the
input notification data.
2 Input
resp
onse
when
there is no
input data
• The communications master outputs
the
following output notification data.
• The communications master has not
ye
t recei
ved input data, so the Input
SID Response remains at 00 hex.
The CIF Unit receives the ou
tput notification
data given on the left.
3 Data
reception
--- The CIF Unit receives data from the serial
line.
-
00 hex
-
-
-
-
None
Input Data
Port Status
Input SID
Output SID
Response
Input Data Type
Input Sub Info
Input Data Length
-
00 hex
-
-
-
-
Output SID
Input SID
Response
Output Data
Type
Output Sub Info
Output Data
Length
Output Data
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