Rs232C Interface - Fujitsu GP 7000F Manual

CHAPTER 12 External Interfaces

12.2 RS232C Interface

Overview The RS232C interface is the interface standard adopted by EIA (Electronic Industries Association)
Electrical Rating Specifications
Connecting cables
148
in the USA in accordance with the CCITT (comite consultatif international telegraphique et
telephonique) recommendation. The connections should be made after the specifications have
carefully been checked for each of the adapters and controllers, since only the limited and necessary
codes in the RS232C standard are supported in them. The RS232C interface is an unbalanced
interface based on JISX5101 (former JISC6361) and CCITT V.24/V28.
Moreover, care must be taken not to confuse the signal names which may differ from equipment to
equipment.
The following rating specifications must be met:
Table 12.4
Input circuits Input thresholds
Input impedance
Maximum allowable input
voltage
Receiving margin
RV element used
Output circuits Output voltages
Output impedance
Maximum output current
DV element used
Use shielded pair cables that meet the following specifications. The signal return lines should be
gathered together to be connected to the SG (signal ground) at both ends.
 DC resistance (per pair, both ways): 300 ohm/km or less
 Capacitance between lines (between pairs): 70 PF/m or less
 Cable length: 100 m or less
 Cable screen: Shielded cables
Table 12.5 lists the definitions of signal line.
Electrical Rating Specifications
ON (0) at +3 V or higher, OFF
(1) at -3 V or lower
3 to 7 Kohm
+-25 V
45% or more
SN75C1406 or SN75189AN
(products of TI) or equivalent
+5 V to +15 V, -5 V to -15 V
300ohm or less
+-0.5 A or less
SN75C1406 or SN75188AN or
equivalent