Chapter 5.
COMMUNICATION DATA TABLE
5 - 1 Basic Communication Data Processing
18
■ Communication data types and formats
● Types of communication data
The communications data are categorized as follow:
• Device related data
• Operating status related data
• Instantaneous flow rate related data
• Integrated flow related data
• Function setup related data
• Parameter setup related data
● Format of communication data
Communication data is classified into the following formats:
●
Numeric data: Data indicating a numeric value (PV, SP, etc.).
●
Bit data: Data where each bit is significant (alarms, etc.). Bit data must
be composed by transmission and decomposed by reception.
■ Communication data storage memory
● Memory type
The communication data are stored in the following two types of memory:
• RAM: Stored data is cleared when the power is turned OFF. However
data can be written to this memory any number of times.
• EEPROM: Stored data is retained even when the power is turned OFF,
whereas data write operations are limited to a total of 100,000
times owing to device characteristics.
● Communication object memory
In communication, it is necessary to read/write data from/into the abovementioned
two types of memory according to the purpose and use. There is a difference
between the object memories as follows:
• RAM: Data is read/written from/into RAM only. If the power supply
is turned off after writing data into RAM, and then it is turned
on again, the data in EEPROM is copied on RAM, so the data in
RAM becomes the same as in EEPROM.
• EEPROM: Data are written in both RAM and EEPROM.
If it is necessary to change the parameters of the CMQ Series frequently by
communication, write data at addresses of RAM. The guaranteed data write count at
the EEPROM addresses is limited to 100,000 times.
Note that the data in RAM is cleared, and the data in EEPROM is copied on RAM if the
power supply to the CMQ Series interrupted.
IMPORTANT
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