Operating Manual

Accu-Wave Chapter 8 Serial Ports, Contact Inputs & Special Fcts
TN Technologies 8-15
Party–Line Communications
This section describes various aspects of setting up and using party-line communications
for multiple gauges.
Setting up a Party-Line
To set up party-line communications from the local keypad and display of each gauge on
the party-line, use the following procedure.
1. Wire all units to the RS-485 common lines as per the wiring instructions in the
Accu-Wave Installation and Maintenance Manual provided with your gauge.
2. For each unit, ensure the “Modify port …” menu communication settings is the
same (baud rate, parity, and handshake). Assign each gauge a unique non–zero
unit number. See page 8-8.
3. In the “Set up port … data tranmission” menu (page 8-10), set up the desired RS-
485 measurement selections, data formats, user messages, etc., for each unit.
After completing the data transmission setup, write down the “must be >=” value
displayed in the “window code” menu item. This is the minimum window code
required to transmit the data set for a particular gauge.
4. Using the “Set up port … data transmission” menu, configure the “master” unit
as follows. (The master unit is usually assigned the lowest unit number, typically
unit #1.)
− Specify that this unit is the master unit.
− Set the window code to be greater than or equal to the largest of the “must be
>=” window code values found for all of the units in step 3.
− Specify an appropriate RS-485 update time (see the next section, “Master
Update Time.”
5. Using the “Set up port … data transmission” menu, configure each of the “slave”
units as follows:
− Specify that the unit is a slave.
− Specify the same (largest) value for the window code as used for the master
unit in step 4.
− Specify that the RS-485 update time is zero (0).