Rs-232C Serial Interface; Hardware Requirements; Figure 5.9 Rs-232C Interface Input Circuit; Figure 5.10 Rs-232C Interface Output Circuit - Fujitsu C145-C037-01EN Product Description

5.4

RS-232C Serial Interface

The RS-232C serial interface is a standard interface of this printer.
5.4.1

Hardware 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.
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

Figure 5.9 RS-232C interface input circuit

+5 V
0 V

Figure 5.10 RS-232C interface output circuit

1000 pF
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