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Responding to Displayed Error Messages
Section 7-2
7-2-6
Communications Errors
This section describes the errors relating to communications with the PLC/
Host that can occur during operation, and their remedies.
• Operation When a Communications Error Occurs
When a communications error occurs, the error message is displayed at
the NT20, and the buzzer sounds. Error messages are displayed when the
“Automatic Reset” memory switch is not set.
Some error messages are displayed even if the “Automatic Reset” memory
switch is set.
• Procedure When a Communications Error Occurs
When an error message is displayed, press the [EXIT] touch switch dis-
played on the screen. The screen display will return to the RUN mode.
• Display of Communications Errors
As shown below, communications errors are displayed in the center of the
screen, together with a classification indicating whether they are receive or
send errors.
Screen When an Error Has Occurred while Receiving
Screen When an Error Has Occurred while Sending
Message
Cause
Remedy
(ACIA)
Parity Error
Framing Error
Overflow Error
Overrun
Communications parameters/
conditions of communications
set incorrectly.
Check whether the parity bit,
frame length, baud rate, stop
bit length, and flow control
settings of the PLC match the
settings of the NT20.
Noise caused data corruption
during communications.
Use a noise-resistant cable if
communications occurs in an
environment with high levels
of noise.
The connectors of the con-
necting cable are not con-
nected correctly.
Reconnect the cable.
Buffer Overflow
(NT20-ST128 only)
The NT20 receive buffer is
full.
Lengthen the command trans-
mission intervals. If this error
occurs frequently, set flow
control for communications.
RECEIVING ERROR
EXIT
<Error Description>
Parity Error
Overrun Error
Overflow Error
Framing Error
Buffer Overflow
Time Out
NAK Received
Unit No. Error
FCS Error
RECEIVING ERROR
EXIT
<Type of error>
Time Out
Summary of Contents for NT20
Page 1: ...Programmable Terminal Cat No V091 E1 01 NT20 USER S MANUAL ...
Page 2: ...NT series Programmable Terminal User s Manual Produced March 2007 ...
Page 3: ...iv ...
Page 5: ...vi ...
Page 9: ...x TABLE OF CONTENTS ...
Page 15: ...xvi ...
Page 21: ...xxii EC Directives 6 ...
Page 37: ...16 Before Operating Section 1 6 ...
Page 153: ...132 Transferring the Resource Data Section 3 11 ...
Page 185: ...164 Numeral Setting Section 4 8 ...
Page 267: ...246 Key to Programs Section 6 8 ...
Page 281: ...260 Specifications Appendix A ...
Page 285: ...264 Transporting and Storing PTs Appendix C ...
Page 303: ...282 Function Restrictions Depending on the Support Tool Appendix I ...
Page 307: ...286 Index ...
Page 309: ...288 Revision History ...