WAGO 750-651, Руководство пользователя

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18 • 750-651 (/xxx-xxx) [TTY-Interface 20mA Current Loop]
Datatransfer
WAGO-I/O-SYSTEM 750
Busklemmen
Status byte
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 IL 2 IL 1 IL 0 BUF_F IA RR TA
TA Transmit acknowledge
RR Receive request
IA Initialization acknowledge
BUF_F Buffer full
IL 0,
IL 1,
IL 2 Input length (number of received characters , which have been stored in the
input data)
0 Constant value must always be 0.
2.1.1.9 Datatransfer
With the control and status byte the controlling of the sending and receive
mode takes place. Requests are indicated by a bit change of state. An assigned
bit indicates execution by adopting the value of the request bit.
Initialization of the module:

Set IR bit in the control byte

Initialization of the module

Transmit/receive functions are blocked

Output/input buffers are erased

Serial interface module will load its configuration data
Transmitting data:

TR

TA: put characters into output bytes

Amount of characters is specified in OL0 to OL2

TR is inverted and read out

Characters are put into output buffer if TR=TA
Receiving data:

RR

RA: data in input bytes characters are available

Amount of characters is specified in IL0 to IL2

Characters in IL0 to IL2 are read out

RA is inverted and read out

All characters are read when RR=RA