65
•
Reading from a Slave: Reading from the slave at the
ModBus address corresponding to the data of interest is
memorized in the registers of the Master. Each instruction
can read up to 16 consecutive words.
•
Writing on a Slave: Data of interest by the Master is
written in the slave at the ModBus address corresponding to
the data to overwrite. Each instruction can write up to 16
consecutive
words.
•
Read/write on a Slave: Normally data read from the slave
is saved in the Master. When the data internal to the TD320
varies by effect of the program, it is useful to write the
modified data into the Slave. Each instruction of read/write
can operate only on 1 word.
9.2.2 ModBus RTU Slave
The protocol ModBus Slave can be configured for all three of the
ports EXP1, and COM2.
With this configuration all of the resources of the terminal are
available to the Master device that is eventually connected.
The following table indicates all of the data (word and bit)
accessible by use of the ModBus protocol. Each area of memory
corresponds to a distinct ModBus address (for the access of a
word or a bit), variable from 0 to 65536.
The read/write access and the value given at startup of the TD240
are shown for each. Depending upon the initialization values, the
following cases occur:
1. “ROM” fixed values defined by the program.
2. “EEP” value stored in EEProm memory, maintained for at
least 10 years even in the absence of power.
3. “TAMP” value stored in RAM with the battery buffer. Also this
data is maintained in the absence of power, but for a limited
time (around 4 to 6 months).
Содержание TD240 series
Страница 1: ...Manuale operatore...
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Страница 6: ...6 3 Mechanical dimensions and installation...
Страница 24: ...24 7 1 Starter Kit Connection of the terminal to the PC...
Страница 27: ...27 7 2 1 Creation of a new project...
Страница 89: ...89 11 Notes Updates...
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