User guide

PlantLinc PLR5000 User’s Guide
P/N 161-09888-001 DATA-LINC Group
17
Number of Disconnects
If, during the course of performing a link test, the link between the Master and the Remote is broken, and the
radios lose carrier detect, the occurrence is recorded in the Number of Disconnects value. The value indicates
the total number of disconnects that have occurred from the time the link test started until the radio was put
into config mode. Under normal operating conditions, the number of disconnects should be 0. One or more
disconnects may indicate a very weak link, the presence of severe interference problems or loss of DC power
to the Master or Repeater if one is present.
Note: a Remote and/or Repeater will record a disconnect if the system Master is placed into configuration
mode or has power interrupted while the Remote and/or Repeater is linked to the Master
Radio Temperature
The radio temperature value is the current operating temperature of the radio in degrees C (Celsius.) For
proper operation, PLR5000 radio modems must be in the range of –4
0
to 75
0
C.
Multipoint Operation
In a multipoint system, a radio modem designated as a Master is able to simultaneously be in communication
with numerous Remotes. In its simplest form, a multipoint network functions with the Master broadcasting its
messages to all Remotes and the Remotes responding to the Master as appropriate.
Traditionally, a multipoint network is used in applications where data is collected from many instruments and
reported back to one central site. As such, the architecture of such a system is completely different from
point-to-point applications. The theoretical maximum number of Remotes that can be configured into a
multipoint network is a function of the data throughput needed from each of the Remotes. For example, if the
network will be polling Remotes once a day to retrieve sparse data, several hundred Remotes could be
configured to a single Master. If, on the other hand, each Remote will be transmitting data at greater levels
then fewer Remotes may be connected to the Master (the overall system will be closer to capacity with fewer
Remotes).
The theoretical limit of a multipoint system is influenced by the following parameters:
• Size of the blocks of data—the longer the data blocks the greater the system capacity
• RS232 baud rate
• The amount of contention between Remotes
• Use of Repeaters—a single Repeater in a multipoint network will decrease overall system
capacity by 50%; more than one Repeater does not further decrease network capacity.