SSI America 7SL instruction manual Serial Interface, Common

D) Serial Interface

For units built with optional RS-485 communication

I		A/A'		A'/A
N
	11				M
S
T		B/B'		B'/B	A
R					S
	12
U					T
M			COMMON		E
E					R
	13
N
T

Maximum cable length: 1.5 km (9/10 mile) at 9600 baud.

NOTE: According to EIA specification for RS-485:

a)The “A” terminal of the generator shall be negative with respect to the “B” terminal for a binary 1 (MARK or OFF) state.

b)The “A” terminal of the generator shall be positive with respect to the “B” terminal for a binary 0 (SPACE or ON) state.

The RS-485 interface can connect up to 31 instruments with the remote master unit (see below).

I	A/A'	A'/A
N
S	11		M
T			A
R	B/B'	B'/B S
U	12		T
M		COMMON	E
E	13		R
N
T

I

N11

S

T

R12

U

M

E13

N T

1 1

7sl-1-00.p65 11 9/17/02, 2:39 PM