ero electronic DPS - Serial Interface; Rs-485 Wiring

21
E.3 SERIAL INTERFACE
RS-485 interface allows to connect up to 31 instrument with the
remote master unit. See Fig. 2.17.
Fig. 2.16 - RS-485 WIRING
The cable length must not exceed 1.5 km at 9600 BAUD.
NOTE: The following report describes the signal sense of the voltage
appearing across the interconnection cable as defined by EIA
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)
21
22
COMMON
20
M
A
S
T
E
R
I
N
S
T
R
U
M
E
N
T
B'/B
B/B'
A/A'
A'/A
I
N
S
T
R
U
M
E
N
T
Fig. 2.17 - CONNECTION OF THE INSTRUMENTS (MAX 31) TO
THE MASTER UNIT BY INTERFACE COMMUNICA-
TION TYPE RS-485
21
22
COMMON
20
M
A
S
T
E
R
21
22
20
I
N
S
T
R
U
M
E
N
T
B'/B
B/B'
A/A'
A'/A