Rs-485 interface, Connection way of the serial interface – CIRCUTOR DHB Series User Manual
Page 27
27
dLY1, dLY2,
dLY3, dLY4,
4, 5, 6, 7
0
LEd1, LEd2,
LEd3, LEd4
4, 5, 6, 7
oFF
P_An
8
InP1
tYPA
8
0_10U
AnL
8
0
AnH
8
99999
bAud
8
19.2
prot
8
r8n1
Addr
8
1
SEt
9
no
SEC
9
0
HOUR
9
not defined
unit
9
off
tESt
9
off
6. RS-485 INTERFACE
DHB-224 programmable digital meters have a serial link in RS-485
standard for the communication in computer systems and with other
devices fulfilling Master function. An asynchronous communication
character protocol MODBUS has been implemented on the serial link.
The transmission protocol describes ways of information exchange be-
tween devices through the serial link.
6.1. Connection Way of the Serial Interface
The RS-485 standard allows to a direct communication of 32 devices
on a single serial link of 1200 m long (at baud rate 9600 b/s). For the
connection of a higher quantity of devices, it is necessary to apply ad-
ditional intermediate-separating systems ( e.g. PD51 converter).