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Helios PD2-6100 Strain Gauge, Load Cell, and mV Meter
RS-485 Connections
The RS-485 connections are made to a five terminal
connector used for Modbus® RTU serial
communications. The RS-485 terminals include
Transmit Data (DO) and (/DO), Receive Data (DI) and
(/DI), and Signal Ground. See Modbus RTU Serial
Communications (serial) on page 44 for more
information.
There are three diagnostic LEDs: Power (PWR)
Transmit Data (TX), and Receive Data (RX) to show
when the meter is transmitting and receiving data
from other devices.
__ __
DI DI DO DO
RS-485
PWR
Figure 22. RS-485 Connection
RS-485 Multi-Drop Connection
When using more than one meter in a multi-drop
mode, each meter must be provided with its own
unique address. The meter address (Slave ID) can be
programmed between 1 and 247. The transmit delay
can be set between 0 and 199 ms. The parity can be
set to even, odd, or none with 1 or 2 stop bits.
To change the meter address:
1.
Press and hold the Menu button for three
seconds to access Advanced Features menu of
the meter.
2.
Press Up arrow until Serial (SEriaL) menu is
displayed and press Enter, Addres is displayed.
3.
Press Enter to change meter address using Right
and Up arrow buttons. Press Enter to accept.
4.
Press Menu button to exit and return to Run
Mode.
RS-485 Serial Converters
To convert the RS-485 to RS-232, use the PDA7485-I
converter. To convert the RS-485 to USB, use the
PDA8485-I converter. See Ordering Information on
page 6 for additional information.
TX
RX
RS-485 Connection Examples
RS-232 to RS-485
Shield
Twisted-Pair
Figure 23. Five-Wire RS-485 Connections
Shield
Twisted-Pair
Figure 24. Three-Wire RS-485 Multi-Drop
Connections
Notes:
1.
Termination resistors are optional, and values
depend on the cable length and characteristic
impedance. Consult the cable manufacturer for
recommendations.
2.
Refer to RS-232 to RS-485 Converter
documentation for further details.
3.
Use shielded cable, twisted-pair plus ground.
Connect ground shield only at one location
20
Instruction Manual
R
R
RS-232 Serial
Connection
DO
DO
DI
DI
to PC
Converter
__ __
DI DI DO DO
R
R
R
RS-232 Serial
Connection
DO
DO
DI
DI
to PC
RS-232 to RS-485
Converter
Meter #1
Last Meter
__ __
__ __
DI DI DO DO
DI DI DO DO
R
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