User`s manual

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6.2 Response Monitoring Time (timer 1) Setting
The response monitoring time (timer 1) clears the receive wait state of the device that receives the response message
when trouble in the device that received the message does not return a response message (result) to the external
device.
When the Q series C24 receives a message from the external device, it monitors the programmable controller CPU
processing time up to the start of transmission of the response message to the external device.
When a message was received, it monitors the external device processing time up to the start of reception of the
response message from the external device.
The following describes the response monitoring time (timer 1) operation.
• If on-demand data is transmitted before a response message during data communications using a MC
protocol, the time up to the start of transmission of the on-demand data is monitored.
(1) Q series C24 operation by response monitoring time (timer 1)
(a) When response monitoring time (timer 1) set to 0ms
After receiving a message, the Q series C24 does not monitor the time up to the start of transmission of a
response message to the external device, but waits infinitely.
After transmitting a message, the Q series C24 does not monitor the time up to the start of reception of the
response message from the external device, but waits infinitely.
(b) When response monitoring time (timer 1) is set to 100ms or longer
After receiving a message, the Q series C24 monitors the time up to the start of transmission of a response
message to the external device and returns the elapsed time to 0 at the start of transmission.
After transmitting a message, the Q series C24 monitors the time up to the start of reception of the response
message from the external device and returns the elapsed time to 0 at the start of reception.
At time-out, the Q series C24 performs the following processing.
• Data communications using a MC protocol
• Stores the error code to the MC protocol transmit error code storage area (buffer memory addresses
25AH, 26AH) for the target interface.
• Transmits a response message (NAK message) to the external device and waits to receive the next
command message.
• Data communications using bidirectional protocol
• Stores the error code to the data transmission result storage area (buffer memory addresses 257H, 267H)
for the target interface and performs transmission processing abnormal completion.
• While waiting to transmit a response message, the Q series C24 does not check the response monitoring
time.
External device
Message
Message
Response message
Response message
Monitoring time Monitoring time
Elapsed time reset Elapsed time reset
Programmable
controller CPU
External
device
Programmable
controller CPU
Monitoring time
On-demand data
Response message
Command message
Elapsed time reset