HM-USB-ISO User Manual
MAN-1008 19/7/2012 v2
Designed and Produced under
Page 3 of 8
ISO 9001:2008 Certification
Step 3) COM Port Number Assignment
After connecting the USB HART Modem and it still connected to the PC, go to Start
Settings
Control Panel
System
Hardware
Device Manager
Ports (COM & LPT), to see what com port
number was assigned to the modem by the Windows operating system. The port labelled
“USB Serial
Port
(COM?)” shows the assigned port
number, where ? is the assigned COM port number.
This port number assignment can be changed by the user.
From the “Device Manager” menu,
select the
USB Serial Port you wish to change. From
the “Properties” page, select “Port
Settings”. Then select
“Advanced”. The COM
port number can be set in the range 1-256. However, we recommend you leave it
at the automatically assigned port number unless you know what you are doing and have a reason to
change it.
Step 4) Connect to HART device/network
The modem can be connected in one of two ways: across the loop load resistor (A
–
B) or across the
HART transmitter terminals (C
–
D). See the relevant Figure 1a, 1b or 1c below.
Figure 1a. Loop Powered HART Transmitter Connection
Figure 1b. 4-Wire HART Transmitter Connection
Figure 1c. Multi-drop HART Transmitter Connection
Step 5) Power the HART device/network
No external power sources are required for the USB HART Modem (HM-USB-ISO) as power is derived
from the USB connection to the PC. However, as shown in Figures 1a, 1b and 1c (above) the HART device
should be powered as per the
manufacturer’s instructions.
Loop
Power
Supply
+
-
HART
Transmitter
+
-
Loop Resistor
A
B
C
D
Loop Resistor
C
A
Power
Supply
+
-
HART
Transmitter
+
-
+
-
D
A
B
Loop
Power
Supply
+
-
H
A
R
T
Tr
a
n
s
m
itt
e
r
+
-
Loop Resistor
B
C
A
D
H
A
R
T
Tr
a
n
s
m
itt
e
r
+
-
H
A
R
T
Tr
a
n
s
m
itt
e
r
+
-
