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6 Communication protocols
The TD329 can communicate with all devices that support the
following serial protocols:
•
ModBus RTU
•
Nais Matsushita master
The terminal has 3 serial ports of communication (COM1, EXP,
COM2), analyzed from the electrical point of view in chapter 3.
Nonetheless, the ports are each managed in a different manner
and will be analyzed separately.
6.1 Managing the communication port
The communication between the TD320 and other devices is
managed by the PLC part of the terminal, thus the configuration of
the port and the instructions must be implemented in the
development environment PLProg 4.xx.
Generally the coils of the Ladder diagram are executed following
the sequential order written in the diagram itself. The instruction
related to the coil at line “n+1” is not executed until the full
completion of the instruction related to the coil at line “n” (for coils
positioned in the same column).
The control of transmission and reception of data is instead
asynchronous
with respect to the cycle of execution of the
Ladder code.
When an instruction of read/write of a device must be executed
(line “n”), control passes immediately to the next instruction (line
“n+1”), without waiting for the data to be effectively read/written.
