7-45
Flag operation in serial communication
Header: No-STX, Terminator: CR
Receiving data:
The “reception done” flag, the “transmission done” flag, and the F159 (MTRN) instruction are related as
follows:
•
For general-purpose serial communication, half-duplex transmission must be used.
•
Reception is disabled when the “reception done” flag R9038 or R9048 is on.
•
When F159 (MTRN) is executed, the number of bytes received is cleared, and the address (write
pointer) in the receive buffer is reset to the initial address.
•
Also, when F159 (MTRN) is executed, the error flag R9037 or R9047, the “reception done” flag R9038
or R9048 and the “transmission done” flag R9039 or R9049 goes off.
•
Duplex transmission is disabled while F159 (MTRN) is being executed. The “transmission done” flag
R9039 or R9049 must be observed.
•
Reception continues even if the error flag R9037 turns on. To resume reception, execute the F159
(MTRN) instruction, which turns off the error flag.
Note:
•
Be aware that the “reception done” flag R9038 or R9048 changes even while a scan is in progress
(e.g., if the “reception done” flag is used multiple times as an input condition, there is a possibility of
different statuses existing within the same scan.) To prevent multiple read access to the special internal
relay you should generate a copy of it at the beginning of the program.
Key Point:
•
The contact numbers in parentheses refer to COM2 port.
Содержание FP E Series
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Страница 29: ...Chapter 2 Specifications and Functions of the Unit ...
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Страница 49: ...Chapter 3 Expansion ...
Страница 56: ...3 8 Terminal layout diagram Note The numbers in the connector are for the first expansion ...
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Страница 67: ...Chapter 5 Installation and Wiring ...
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Страница 91: ...Chapter 6 High speed counter Pulse Output and PWM Output functions ...
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Страница 151: ...Chapter 7 Communication Cassette ...
Страница 202: ...7 52 Procedure of communication In the following example the Micro Imagechecker is connected to COM1 port ...
Страница 210: ...7 60 The values of DT50 and DT51 are written in DT0 and 1 of PLC ...
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Страница 249: ...Chapter 9 Precautions During Programming ...
Страница 260: ...9 12 Example 2 Using the CT instruction between JP and LBL instructions ...
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Страница 269: ...Chapter10 Specifications ...
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Страница 287: ...Chapter 11 Dimensions ...
Страница 290: ...11 4 11 1 3 Expansion Unit FPG XY64D2T FPG XY64D2P FPG EM1 ...
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