Chapter6 Communication Mode
6 - 4
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Sending data
EH-SIO sends a packet to external device, shortly after receiving the packet transmitted by TRNS 9 (data sending
command) from CPU module. If Message composition is registered at initial setting, EH-SIO will process a
sending packet automatically and will send it.
Figure 6.4 Structure of data transmitting
< Variation of data transmission >
There are three methods of data send: sending only, receives after sending, send after receiving.
Error detection
EH-SIO is able to detect errors in the hardware and can check receiving data. When error of hardware (ROM error,
RAM error, WDT error, etc.) is detected, error information is shown on the LED display, and operation stops. When
error in receiving data (parity error, framing error, etc.) is detected, error information is shown on the LED display,
and the information is stored in a receiving buffer as one packet. When the packet of error information is read, the
error code is stored in a return code area. In addition, the errors of receiving data are classified into "Warning", and
EH-SIO continues operation
.
Figure 6.5 Detection of
warning (receiving error)
External device
Command
Packet
Data send
Packet
Start character
Check Code
Stop character
Processed send packet
Send packet
CPU module
EH-SIO
Send data
TRNS 9
CPU module
EH-SIO
External device
Packet 1
Data
Reception
Packet 1
Data
Reception
Receiving Buffer
Packet 3
Open
Error information
Packet 3
Packet 2
Parity Error
Содержание EH-150 Series
Страница 1: ...HITACHI PROGRAMMABLE CONTROLLER Serial Communication Module EH SIO APPLICATION MANUAL NJI 443F X ...
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Страница 10: ...M E M O ...
Страница 30: ...Chapter 4 Installation 4 10 M E M O ...
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