Keyence N-410 User Manual download pdf (Page 99)

Serial Communication

6-3

6-2 Details of Data Communication

This section describes the communication protocols and formats used for data communication.

Communication Protocol

The N-410 Series supports the following four handshaking protocols (data transfer procedures).

Both multi-drop Link Mode Data Communication (Auto-polling/manual polling), multi-head mode

data communication operate in the same way.

 No handshake

• The read data is sent to the host computer constantly. In other words, transmission is unregulated.

 PASS/RTRY protocol

• After read data is sent, the N-410 waits for a response (PASS or RTRY) from the host computer.

If a PASS (normal function) signal is sent to the N-410, one transmission has been completed and

the next can begin.

The N-410 does not send a response to a PASS signal.

• If the N-410 receives a RTRY (resend request) while waiting for a PASS signal, it resends the data and

resumes waiting for a PASS signal.

The N-410 does not reply to a RTRY signal if it has already received a PASS signal.

• Reading can occur while the device is waiting for a PASS signal. If this happens, the read data will

be stored in the N-410 send buffer.

If the send buffer capacity is exceeded, the N-410 will send an OVER message to the host computer all

data in the send buffer will be cleared.

In this case, the N-410 will halt and will reactivate upon receiving an OVCLR signal or having the

TEST switch pressed.

Refer to "Send Buffer Capacity" (Page 4-9) for more information on send buffer capacity and

the OVER signal.

N-410

Read data

N-410

Read data

Response (PASS,RTRY)

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Keyence N-410 User Manual Page 99