Mounting
The DIN rail moun ng clip is compa ble with widely used 35mm EN 50022 rails. It can be snap mounted and removed
from the moun ng rail without tools for quick installa on 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 posi ve side to DTR (pin 4) and nega ve
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
connected to the ma ng RS-232 port. Only transmit, receive,
and ground are required for communica ons.
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 connec ng the
MicroLink-HM to the RS-232 serial port requires
only 4 wires. If external power is used then only
transmit, receive, and ground are needed on the
RS-232 port side.
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Power from DTR line
External power supply
