Land 4500 MKII Premier, Руководство по эксплуатации и обслуживанию

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Model 4500 Premier Dust and Opacity Monitor
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A3-14 MODBUS Connections
The communication protocol fitted as standard on the Model 4500 Premier is the MODBUS protocol.
Based on the RS232 or RS485 hardware standards it provides direct access to system data via the T-
Box terminal connections 38 - 43. RS485 connections may be ither 2 wire half duplex or 4 wire full
duplex.
The MODBUS PCB is manufactured to accept RS 232 or RS 485 connection using the switch selector
fitted inside the termination box. The switch is located inside the T-Box, and is clearly labelled.
IMPORTANT
Where RS 232 is selected as the Modbus communications protocol, the existing 120
Ω
termination resistor requires disconnecting between terminals 40 and 41 inside the T-Box.
The resistor must be retained for RS 485 Modbus communications.
WARNING
Isolate the mains supply before making any electrical adjustments to the T-Box. This
instrument must be earthed/grounded.
38 39 40 41 42 43
(Tx) (Rx) Common
RS 232
38 39 40 41 42 43
A (Rx)
B (/Rx)
Y (Tx)
Z (/Tx)
Common
RS 485, 4 Wire, full duplex
38 39 40 41 42 43
A
B Common
RS 485, 2 Wire, half duplex
(Tx) (Rx) COM Y (Tx)
Z (/Tx)
A (Rx)
B (/Rx)
COM
REMOTE DEVICE
(Tx)
(/Tx) (Rx)
(/Rx) COM
REMOTE DEVICE
REMOTE DEVICE