Point-To-Point Wiring; Multi-Point Wiring - GE DigitalFlow GF868 Programming Manual

Chapter 6. Serial Communications

6.5.2 Point-To-Point Wiring

Standard factory wiring of the RS485 serial interface is configured for point-to-point wiring. That is, a single Model
GF868 may be wired directly to a single personal computer. To connect the RS485 serial interface, refer to Figure 9 on
page 79 and complete the following steps:
Note: For compliance with the European Union's Low Voltage Directive, a transparent plastic shroud protects the
electrical connections. The shroud must remain in place, except while wiring the unit. Reinstall the shroud
after the wiring has been completed.
1. Disconnect the main power to the electronics console and open the cover.
WARNING! Dangerous voltages exist within the electronics console. Do not perform any wiring
operations until the main power to the unit has been disconnected.
2. Remove the clear plastic shroud that covers the electrical connectors.
3. Using a twisted-wire pair, connect the XMT+ terminal of the barrier strip to the T+/R+ terminal of the PC's RS485
adapter and connect the XMT– terminal of the barrier strip to the T-/R- terminal of the PC's RS485 adapter (see the
documentation provided with the RS485 adapter for details).
Note: The XMT+ terminal on the barrier strip is the screw opposite the red wire connection and the XMT– terminal
on the barrier strip is the screw opposite the green wire connection.
4. Reinstall the clear plastic shroud, close the cover to the electronics console and reconnect the main power.
The RS485 serial interface is now ready for point-to-point operation. However, the installed version of the Model
GF868 software must be Version 3G or higher to support RS485 operation. If necessary, contact the factory for
information about a software upgrade.

6.5.3 Multi-Point Wiring

The standard point-to-point wiring configuration for the serial interface converter may be modified to permit the use of
a multi-point wiring arrangement. In a multi-point RS485 system, one flowmeter (the master) is connected to the
personal computer, while a number of additional flowmeters (the slaves) are chained together and connected to the
master flowmeter. In order to implement such a system, the
must be changed.
IMPORTANT:
The serial interface converter in the last slave unit in the chain should not be reconfigured.
80
DIP
switch settings inside each serial interface converter
DigitalFlow™ GF868 Programming Manual (2-Channel)