ProtEX-MAX PD8-765 Explosion-Proof Process & Temperature Meter
Instruction Manual
33
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
There are two diagnostic LEDs: Transmit Data (TX),
and Receive Data (RX) to show when the meter is
transmitting and receiving data from other devices.
Figure 20. RS-485 Connections
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 (
SErL
) menu is
displayed and press Enter,
Addr
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.
Three-Wire Connections
In order to wire the five pins for use as a three-wire
half-duplex RS-485 connection, it is necessary to
create a jumper connection between DI to DO and /DI
to /DO- as shown below.
Figure 21. Three-Wire RS-485 Connections
__ __
DI
DI DO DO
