Multi-Point Wiring - GE DigitalFlow DF868 Programming Manual

Multi-Point Wiring

Reconfiguring a Serial
Interface Converter
Serial Communications
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
switch settings inside each serial interface converter must be changed.
IMPORTANT:
The serial interface converter in the last slave unit in
the chain should not be reconfigured.
To reconfigure a serial interface converter for multi-point wiring,
complete the following steps:
1. Disconnect the main power to the electronics console and open the
cover.
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. Remove the serial interface converter mounting bracket by
removing the standoff located just below the
and the grounding screw to its left (see Figure 6-2 on page 6-6).
4. Loosen the two screws that fasten the
mounting bracket, and remove the serial interface converter from
the bracket.
5. Use a small screwdriver to pry open the plastic case of the serial
interface converter, as shown in Figure 6-2 on page 6-6.
The serial interface converter contains a main printed circuit board
and a daughter printed circuit board. The daughter board has a small
terminal block attached to it and the main board has a
SW1
( ) mounted near the center of the board.
6. Locate the switch assembly on the main board, and move the
switch in position 1 from ON to OFF. The standard ON state for
this switch is for point-to-point operation, while the OFF state is
needed for multi-point operation. See Table 6-2 on page 6-6 for
the proper settings of all four switches on the switch assembly.
!WARNING!
RS232
DB9
connector to the
March 2008
DIP
terminal block
DIP
switch
6-5