Fujitsu M600, M200 12.2 RS232C Interface, 148, Electrical Rating Specifications, Connecting cables

CHAPTER 12 External Interfaces

12.2 RS232C Interface

Overview The RS232C interface is the interface standard adopted by EIA (Electronic Industries Association) 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.

Electrical Rating Specifications

The following rating specifications must be met:

Table 12.4 Electrical Rating Specifications

Input circuits	Input thresholds	ON (0) at +3 V or higher, OFF
		(1) at -3 V or lower
	Input impedance	3 to 7 Kohm
	Maximum allowable input	+-25 V
	voltage
	Receiving margin	45% or more
	RV element used	SN75C1406 or SN75189AN
		(products of TI) or equivalent
Output circuits	Output voltages	+5 V to +15 V, -5 V to -15 V
	Output impedance	300ohm or less
	Maximum output current	+-0.5 A or less
	DV element used	SN75C1406 or SN75188AN or
		equivalent

Connecting cables

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.

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