Chapter 5 Master Control Unit
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Quick flashing: with a frequency of 4Hz
5.4.4 Operating Principle
The DB9 interface of the LK249 module receives the data sent from the I/O device. Upon conversion
via RS485, the signal is converted into a signal supported by the bottom protocol, with the interfering
signal coming from the field eliminated via an isolator. The signal is transmitted to MUC for
processing.
Figure 5-20 LK249 Internal Schematic Diagram
The DP master station in the master frame is in operation. The DP master station in the slave frame is
in the listening mode. The data is synchronized periodically between the DP master stations. When
the controller switches between the master and slave machines, the DP master station also switches
accordingly.
5.4.5 Terminal Definition
The LK249 module has two DB9 interfaces with each redundancy, which used to connect the IO
devices and DP master station communication module in the redundancy cabinet.
Figure 5-21 DB9 Interface Schematic Diagram
Table 5-8 DB9 Pin Signal Definition
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