Fujitsu C145-C037-01EN manual RS-232C Serial Interface, RS-232C interface input circuit

5.4RS-232C Serial Interface

The RS-232C serial interface is a standard interface of this printer.

5.4.1Hardware requirements

Signal levels:

–3 V or lower for a mark condition (logical 1) +3 V or higher for a space condition (logical 0)

Input circuit:

An MC1489AL or equivalent is used to convert from the RS-232C level to the TTL level.

Figure 5.9 shows the RS-232C interface input circuit.

Figure 5.9 RS-232C interface input circuit

Output circuit:

An MC1488L or equivalent is used to convert from the TTL level to the RS-232C level. A 1000-pF capacitor suppresses noise on the output signal line.

Figure 5.10 shows the RS-232C interface output circuit

+5 V

1000 pF

0 V

Figure 5.10 RS-232C interface output circuit

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