Chapter 1 Introducing the PA912 Module
6F8C1259
1.1.2 Specifying medium/high speed TC-net I/O loop scan
"Medium speed" and "high speed" is available as the TC-net I/O loop scan
transmission speed. When a short response time is required between the
controller and the slave I/O devices, the response speed between the slave I/O
devices and the nv controller can be enhanced by setting the slave I/O devices
to "high speed".
Input and output areas of the slave I/O devices process data (cyclic data) are
both divided into high speed area (first half) and medium speed area (latter
half) by 128 byte sizes. The high speed area (first half) is allocated for high
speed transmission of the TC-net I/O loop, and the medium speed area (latter
half) is allocated for medium speed transmission. Thus, a relation is
established by setting the input and output addresses of the slave I/O devices
in the high speed area (first half) or the medium speed area (latter half).
The input and output areas for the slave I/O devices process data (cyclic data)
can be specified as the high speed or medium speed area via the nV-Tool by
using a module parameter "High-speed scan byte size (input/output)" of the
PA912-M/PA912-NM module. The setting method is described in "Chapter 3:
Setting."
It should be noted that the RAS information is fixedly set to medium speed.
Figure 1-3 Specification of medium/high speed TC-net I/O loop scan
nv Controller
（
）
TC-net I/O loop
common memory
TC-net I/O loop
common memory
Fixed at medium
speed
Scan
transmission
Output device
Adr=0
PROFIBUS
slave I/O devices
Output device
Adr=128
Input device
Adr=0
Input device
Adr=128
I/O input
TC-net I/O
loop
High speed
Medium speed
Medium speed
High speed
High speed
Medium speed
High speed
High speed
Medium speed
Medium speed
High speed
0
128
0
128
High speed
area
High speed
area
Medium
speed area
Medium
speed area
Fixed at
medium
speed
Medium speed
I/O output
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