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Serial Communications Section 6-1
Related Auxiliary Area Flags for Serial Port 2
Note In the same way as for the existing 1:N NT Link, the status (communicating/
not communicating) of PTs in Serial PLC Links can be checked from the Poll-
ing Unit (CPU Unit) by reading the Serial Port 2 Communicating with PT Flag
(A393 bits 00 to 07 for unit numbers 0 to 7).
Name Address Details Read/write Refresh timing
Serial Port 2
Communica-
tions Error Flag
A392.04 Turns ON when a com-
munications error occurs
at Serial Port 2.
ON: Error
OFF: Normal
Read • Cleared when power is turned ON.
• Turns ON when a communications error
occurs at Serial Port 2.
• Turns OFF when the port is restarted.
• Disabled in peripheral bus mode and NT
link mode.
Serial Port 2
Communicating
with PT Flags
(See note.)
A393.00 to
A393.07
When Serial Port 2 is
being used in NT link
mode, the bit correspond-
ing to the Unit performing
communications will be
ON. Bits 00 to 07 corre-
spond to unit numbers 0
to 7, respectively.
ON: Communicating
OFF: Not communicating
Read • Cleared when power is turned ON.
• Turns ON the bit corresponding to the
unit number of the PT/Polled Unit that is
communicating via Serial Port 2 in NT
link mode or Serial PLC Link mode.
• Bits 00 to 07 correspond to unit numbers
0 to 7, respectively.
Serial Port 2
Restart Bit
A526.00 Turn ON this bit to restart
Serial Port 2.
Read/write • Cleared when power is turned ON.
• Turn ON to restart Serial Port 2, (except
when communicating in peripheral bus
mode).
Note: The bit is automatically turned OFF
by the system when restart process-
ing has been completed.
Serial Port 2
Error Flags
A528.00 to
A528.07
When an error occurs at
Serial Port 2, the corre-
sponding error bit is
turned ON.
Bit 00: Not used.
Bit 01: Not used.
Bit 02: Parity error
Bit 03: Framing error
Bit 04: Overrun error
Bit 05: Timeout error
Bit 06: Not used.
Bit 07: Not used.
Read/write • Cleared when power is turned ON.
• When an error occurs at Serial Port 2, the
corresponding error bit is turned ON.
• The flag is automatically turned OFF by
the system when Serial Port 2 is
restarted.
• Disabled during peripheral bus mode.
• In NT link mode, only bit 05 (timeout
error) is enabled.
In Serial PLC Link mode, only the following
bits are enabled.
• Errors at the Polling Unit:
Bit 05: Timeout error
• Errors at Polled Units:
Bit 05: Timeout error
Bit 04: Overrun error
Bit 03: Framing error
Serial Port 2 Set-
tings Changed
Flag
A619.02 Turns ON when the com-
munications conditions of
Serial Port 2 are being
changed.
ON: Changed
OFF: No change
Read/write • Cleared when power is turned ON.
• Turns ON while communications condi-
tions settings for Serial Port 2 are being
changed.
• Turns ON when the CHANGE SERIAL
PORT SETUP instruction (STUP(237)) is
executed.
• Turns OFF when the changes to settings
are completed.
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