Denso AT21B-SM Manual de usuario descargar pdf (Pagina 47)

Chapter 9 Communication

9.1 RS-232C Interface

With the RS-232C interface being selected, the scanner uses asynchronous data transmission and

communicates with the host computer or external equipment via the RS-232C. You can set various

communications conditions using the Bar coded parameter menu or configuration software (Scanner Setting).

Barcode data read is transferred in the following format.

(1) Communications protocol

You can select either no protocol mode or ACK/NAK mode.

No protocol mode (default)

If the CTS signal is at a high level (Enable transmission), the scanner transmits barcode data read.

Note: The configuration software (Scanner Setting) provides CTS timeout settings from 100 ms to

9.9 s in 100-ms increments and two CTS signal control choices “controlled” and “not controlled.”

ACK / NAK mode

If the CTS signal is at high level (Enable transmission), the scanner transmits barcode data read. After that, the

scanner waits for and then processes a response. If the response is an ACK, the scanner normally ends the

transmission; if it is a NAK, the scanner transmits the barcode data again.

Note: The configuration software (Scanner Setting) provides CTS timeout and ACK/NAK response settings

each from 100 ms to 9.9 s in 100-ms increments.

(2) RTS signal control protocol

You can select either the scanner ready mode or the data ready mode.

Scanner ready mode(default)

The RTS signal goes High and stays at a high level when the scanner is ready to communicate at power on.

Make sure that the RTS signal is at a high level when transmitting a command from the host to the scanner.

Data ready mode

The RTS signal goes High before the scanner transmits data to the host and goes Low after the data

transmission is completed.

Commands can be transmitted from the host to the scanner regardless of the level of the RTS signal. However,

there is a short time when commands cannot be transmitted to the scanner after power has been turned on.

(3) Transmission speed

There are six transmission speeds available, ranging from 4800 bps to 115200 bps (default: 9600 bps).

(4) Transfer Characters

Transfer Characters that the scanner transfers are all ASCII codes. The frame format has the following

parameters.

Data bits : 7 bits or 8 bits (default)

Parity : Odd, Even, or None (default)

Stop bits : 1 bit (default) or 2 bits

Note: When data contains binary data or 2-byte codes, selecting “7 bits” for the data bits transfers the 2-byte

codes with the most significant bits trimmed.

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Denso AT21B-SM Manual de usuario Pagina 47