Mitsubishi Electronics MAM-AM6 Setting the operating mode on the DIP switch, RS422 Connection

RS485 / RS422						Interfaces
Setting the operating mode on the DIP switch
	Operating mode	DIP 1	DIP 2	DIP 3	DIP 4	DIP
	Two-wire RS485 with termination	1	1	1	1	1111
	Two-wire RS485 without termination	0	0	1	1	0011
	Four-wire RS485 without termination	0	0	0	0	0000
	Four-wire RS485 with termination of receive cable	1	1	0	0	1100
	RS422	0	0	0	0	0000

Tab. 4-1:Setting the operating mode on the DIP switch

NOTE

RS485 stipulates that the cables should be terminated at both ends of the transmission sec- tion. The termination prevents signal reflections in the cables and in times of no data trans- mission, enforces a defined idle state on the bus. This termination can be implemented using, for example, specific resistors at the screw terminal. It can also be implemented via the DIP switches on the Mitsubishi Alarm Modem.

RS422 Connection

R+	R–	T–	T+	(0V)
				COM2	Device B
					R+
					R–
					T–
					T+

Fig. 4-7:

The receiving lines are to be connected to R+ (other end T+) and

R- (other end T-), the sending lines to T+ (other end R+) and T- (other end R-)

according to the opposite sketch.

RS485 2-wire connection (2-wire bus system, half-duplex)

In this operating mode, transmit cables and receive cables are interconnected. If the Mitsubishi Alarm Modem is installed at the beginning (first station) or end (last station) of the bus system, the bus system must be terminated by setting the DIP switches accordingly.

R+	R–	T–	T+	(0V)
				COM2	Slave 1
					R+/T+
					R–/T–

Bus Master Slave 2

R+/T+

R–/T–

Slave 3

R+

R–

T+

T–

Fig. 4-8:

The twisted pair cable is to be connected to T+ to T+ or R+ and for

T- to T- or R-

according to the opposite sketch.

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