17: USER COMMUNICATION INSTRUCTIONS
OPENNET CONTROLLER USER’S MANUAL 17-25
User Communication Error
When a user communication error occurs, a user communication error code is stored in the data register designated as a
transmit status in the TXD instruction or as a receive status in the RXD instruction. When multiple errors occur, the final
error code overwrites all preceding errors and is stored in the status data register.
The status data register also contains transmit/receive status code. To extract a user communication error code from the
status data register, divide the value by 16. The remainder is the user communication error code. See pages 17-9 and 17-21.
To correct the error, correct the user program by referring to the error causes described below:
User Communication Error Code
User
Communication
Error Code
Error Cause Transmit/Receive Completion Output
1
Start inputs to more than 5 TXD instructions are
on simultaneously.
Transmit completion outputs of the first 5 TXD
instructions from the top of the ladder diagram
are turned on.
2 Transmission destination busy timeout Goes on after busy timeout.
3
Start inputs to more than 5 RXD instructions with
a start delimiter are on simultaneously.
Among the first 5 RXD instructions from the top
of the ladder diagram, receive completion out-
puts of RXD instructions go on if the start delim-
iter matches the first byte of the received data.
4
While a RXD instruction without a start delimiter
is executed, another RXD instruction with or with-
out a start delimiter is executed.
The receive completion output of the RXD instruc-
tion at a smaller address goes on.
5 — Reserved ——
6 — Reserved ——
7
The first byte of received data does not match
the specified start delimiter.
No effect on the receive completion output.
If incoming data with a matching start delimiter
is received subsequently, the receive completion
output goes on.
8
When ASCII to binary or ASCII to BCD conversion
is specified in the receive format, any code other
than 0 to 9 and A to F is received. (These codes
are regarded as 0 during conversion.)
The receive completion output goes on.
9
BCC calculated from the RXD instruction does
not match the BCC appended to the received
data.
The receive completion output goes on.
10
The end delimiter code specified in the RXD
instruction does not match the received end
delimiter code.
The receive completion output goes on.
11
Receive timeout between characters
(After receiving one byte of data, the next byte is
not received in the period specified for the
receive timeout value.)
The receive completion output goes on.
12
Overrun error
(Before the receive processing is completed, the
next data is received.)
The receive completion output goes on.
13
Framing error
(Detection error of start bit or stop bit)
No effect on the completion output.
14
Parity check error
(Error is found in the parity check.)
No effect on the completion output.
15
TXD1/RXD1 (or TXD2/RXD2) instruction is exe-
cuted while the communication selector DIP
switch is not set to select user communication
mode for the RS232C port 1 (or RS232C port 2).
No effect on the completion output.
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