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Examples:
Process proceeds
200
190
SP2 = 200
AL.MD = LTCH
Process proceeds
200
190
3-7 RS-485 Communication
Using a PC for data communication is the most economic way.
The signal is transmitted and received through the PC
communication Port (generally RS-232). Since a standard PC
can't support RS-485 port, a network adaptor (such as SNA10A,
SNA10B) has to be used to convert RS-485 to RS-232 for a PC if
RS-485 is required for the data communication. Many RS-485
units (up to 247 units) can be connected to one RS-232, that is a
PC with 4 comm ports can communicate with 988 units. It is quite
economic.
200
ON
190
AL.HY = 10.0
AL.FN = PV.H.A
200
ON
190
UM0L911C
Figure 3.3
Normal Process Alarm
200
200
190
190
Figure 3.4
Latching Process Alarm
200
200
190
190
200
190
OFF
200
190
37
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