Mounting
The DIN rail mounting clip is compatible with widely used 35mm EN 50022 rails. It can be snap mounted and removed
from the mounting rail without tools for quick installation and servicing.
Power Supply
The MicroLink-HM is powered through the 9-pin RS-232
connector using the RS-232 Data-Terminal-Ready (DTR)
handshake line - pin 4. When using DTR for power, no external
power supply is required.
An external DC power supply in the 5 to 30Vdc range can also
be used. Connect the positive side to DTR (pin 4) and nega-
tive to Ground (pin 5). Maximum supply current ranges from
2mA at 30 volts to 10.5mA at 5 volts. The RS-232 transmit and
receive will share the ground (pin 5) with the power supply
ground. If external power is used then DTR should not be con-
nected to the mating RS-232 port. Only transmit, receive, and
ground are required for communications.
5 - GROUND
2 - RX ←
3 - TX →
4 - DTR (5-30Vdc)
Figure 2. DB-9 Wiring Diagram
HART Status LED
Power
Supply
RS-232
Driver/Rcvr
HART
Modem
Microcontroller
Modbus Register
Tables
TX
RX
CD
RTS
1
2 - RX
3 - TX
4 - DTR
5 - GND
6
7
8
9
9-Pin RS-232
D-Sub Connector
HART Loop
Terminals
HART Status LED
MicroLink-HM Block Diagram
RS-232 Cable Schematic
The RS-232 extension cable connecting the Mi-
croLink-HM to the RS-232 serial port requires only
4 wires. If external power is used then only trans-
mit, receive, and ground are needed on the RS-232
port side.
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5;
7;
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Power from DTR line
External power supply
