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RS-232C Units Section 6-2
6-2-5 Word Allocations for Communications Status
The RS-232C Unit is allocated one word (16 points) in the IN Area of the Mas-
ter Unit. This word is configured as illustrated in the following diagram, and is
used to communicate the communications status of RS-232C ports 1 and 2 to
the Master Unit.
Bit Name Function
0 8 Transmission
Ready Flag
0: Transmitting data
1: Transmission enabled (no data transmitted)
When writing data to other ports (SEND com-
mand), check to make sure this bit is 1 (ON)
before starting.
1 9 PLC Setup Error
Flag
0: System parameter setup normal
1: System parameter setup error
2 10 Receiving Flag 0: No data is being received
1: Data is being received
3 11 Received Flag 0: No data in the reception buffer
1: Data in the reception buffer
When reading data from other ports (RECEIVE
READ DATA command), check to make sure this
bit is 1 (ON) before starting.
4 12 Parity Error Flag 0: No parity error
1: Parity error
When a parity error occurs, make sure that the
parity setting for the RS-232C Unit and the RS-
232C device are the same.
5 13 Overrun Error Flag 0: No overrun error
1: Overrun error
When an overrun error occurs, make sure that
the baud rate setting for the RS-232C Unit and
the RS-232C device are the same.
6 14 Framing Error Flag 0: No framing error
1: Framing error
When a framing error occurs, make sure that the
character format setting (data length, parity, No.
of stop bits) for the RS-232C Unit and the RS-
232C device are the same.
7 15 Receive Buffer
Overflow Flag
0: No overflow in the reception buffer
1: Reception buffer overflow (Not possible to read
receive data)
When the reception buffer overflows it is neces-
sary to either reset or restart the RS-232C Unit,
or reset (initialize) the RS-232C port at which the
overflow occurred.
Port 2 status Port 1 status
Bit
Bits 0, 8: Transmission Ready Flag
Bits 1, 9: System Parameter Setup Error Flag
Bits 2, 10: Receiving Flag
Bits 3, 11: Received Flag
Bits 4, 12: Parity Error Flag
Bits 5, 13: Overrun Error Flag
Bits 6, 14: Framing Error Flag
Bits 7, 15: Receive Buffer Overflow Flag
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