LG G3L-PUEA User Manual page 40

CHAPTER 6 COMMUNICATION FUNCTION
6.1.8 High speed link speed calculation
1) Overview
High speed link data transmission speed is determined by a variety of factors because one
block data should pass the path as like Figure 6.30 until it can be saved in the receiving area
of another station from that of one station.
In order to send the data through communication from one station to another station in Figure
6.30, there are 3 paths to pass and the required time for each path determines the sending
time.
Table 6.5 shows the major path of data transmission and the factor that effects to the time for
each path.
Items
1
2
3
As the data delivery from(to) PLC CPU to(from) communication module is executed at the
point that PLC user program is finished, the PLC user program scan time can be a major factor
of data transmission and if you select 'PLC information' from GMWIN online menu, you can
find max/min/current program scan time. And for communication module to send the data, it is
required to wait the Poll of master module.
PLC - CPU(A)
When PLC user program scan
finished, data delivery to
communication module
Communication module
(station 1)
CPU data sending to media
Data sending
Figure 6.30 Data transmission path through communication module
Path
PLC CPU(A) --> communication module
(station 1)
Communication module (station1)--
>communication module(station2)
Communication module (station 2) -->
PLC CPU(B)
Table 6.5 Data transmission path and time factor
Communication module (station 2)
Data delivery to PLC after receiving
Communication cable
time+communication O/S scan time
6-25
PLC - CPU(B)
When PLC user program
scan finished, data receiving
in communication module.
the data
Data receiving
Factor to effect the Time
PLC-A program scan time
Communication scan
PLC-B program scan time