Specifications

December 2008 Page 19–3
Chapter 19. Party Line Data (PLD) Module
19
19.2.2 Applications Using Internal
Addressing
The PLD Module’s internal address mode capa-
bility enables you to make remote connections to
RS-232 devices that do not have their own internal
address capability. Some examples of these
devices are smart switches, meters, and other
IEDs (Intelligent Electronic Devices). A typical
PLD application using internal addressing is
shown in Figure 19-2. As with applications using
external addressing, the master unit communicates
with just one remote device at a time, so only one
DS0 time slot, or channel, is required. Thus, with
internal addressing, you can use a single channel
to poll as many as 255 RS-232 devices from a
single terminal. Note that with internal
addressing, the communication between the
master unit and all target devices is at the
maximum 9600 bps data rate.
You set up this type of application with one
FOCUS terminal connected to an asynchronous
RS-232 device. This typically is a PC running a
terminal emulation program. The connection can
either be direct or via modem, as shown in Figure
19-2. The connection between the PLD module’s
interface (DCE) and the RS-232 device requires a
9-pin sub “D” connector wired to the “TXDATA,’
“RXDATA,” and “SIG GND” of the RS-232
device (see “Hardware Installation and
Connections” later in this chapter for specific
wiring examples).
Figure 19–2.
PLD Application Using Internal Addressing.