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6F3B0250
Basic Hardware and Function
261
7. Instructions
CPU register
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T1S RS-485 port (T1S only)
<Receiving>
When the instruction input is ON, one set of message (from start character to the trailing code)
which is received by the RS-485 port is read from the receive buffer, and stored in the CPU
registers. The transfer size is fixed to 256 words. The execution status and the message length (in
bytes) are stored in the status flag.
The instruction input must be kept ON until the receiving operation is complete.
Example
Source designation Transfer size Destination designation
D0000 H0030 D0002 00256 (fixed) D0005 H0004
D0001 00000 D0003 Execution status D0006 00100
D0004 Messa
g
e len
g
th
T1S RS-485 port D0100 (CPU register)
When R0000 is ON, one set of received message is read and stored in D0100 and after.
Execution status:H0000 ... Normal complete
H0001 ... Communication error (parity error, framing error)
H0002 ... Message length over (more than 512 bytes)
H0003 ... Receive buffer over flow
H0004 ... Receive time-out (from start character to the trailing code)
Baudrate Time-out settin
g
300, 600, 1200 bps 30 seconds
2400 bps 15 seconds
4800 bps 7 seconds
9600 bps 3 seconds
19200 bps 1.5 seconds
Message length: 0 .............. No receive message
1 to 512 ... Message length in bytes
Note
·
The XFER instruction is not executed as error in the following cases. In these cases, the instruction
error flag (ERF = S051) is set to ON. If the ERF is set to ON once, it remains ON until resetting to
OFF by user program.
(1) The leading address for the RS-485 port designation is other than 0.
(2) Transfer size is other than 256.
(3) Mode setting of the RS-485 port is not the free ASCII mode.
(4) This instruction is programmed in the sub-program #1.
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