Campbell Scientific CR3000 Micrologger - Manual (Page 356)

Section 8. Operation
356
Though usually unnoticed, a short burst of SDC communication occurs at
power-up and other times when the datalogger is reset, such as when
compiling a program or changing settings that require recompiling. This
SDC activity is the datalogger querying the SDC to see if the integrated
keyboard / display is available.
When DevConfig and PakBus Graph retrieve settings, the CR3000
queries the SDC to determine what SDC devices are connected. Results
of the query can be seen in the DevConfig and PakBusGraph settings
tables. SDC queries occur whether or not an SDC device is attached.
8.5 PakBus Overview
Read More! This section is provided as a primer to PakBus ® communications.
More information is available in PakBus Networking Guide, available at
www.campbellsci.com.
The CR3000 communicates with computers or other Campbell Scientific
dataloggers via PakBus
® . PakBus ® is a proprietary telecommunications protocol
similar in concept to IP (Internet protocol). PakBus ® allows compatible Campbell
Scientific dataloggers and telecommunications peripherals to seamlessly join a
PakBus
® network.
8.5.1 PakBus Addresses
CR3000s are assigned PakBus ® address 1 as a factory default. Networks with
more than a few stations should be organized with an addressing scheme that
guarantees unique addresses for all nodes. One approach, demonstrated in figure
PakBus Network Addressing
(p. 357)
, is to assign single-digit addresses to the first
tier of nodes, double-digit to the second tier, triple-digit to the third, etc. Note that
each node on a branch starts with the same digit. Devices, such as PCs, with
addresses greater than 4000 are given special administrative access to the network
PakBus addresses are set using DevConfig, PakBusGraph, CR3000 Status table,
or with an integrated keyboard / display. DevConfig (Device Configuration
Utility) is the primary settings editor for Campbell Scientific equipment. It
requires a hardwire RS-232 connection to a PC and allows backup of settings on
the PC hard drive. PakBusGraph is used over a telecommunications link to
change settings, but has no provision for backup.
Caution Care should be taken when changing PakBus ® addresses with
PakBusGraph or in the Status table. If an address is changed to an unknown
value, a field visit with a laptop and DevConfig may be required to discover the
unknown address.
8.5.2 Nodes: Leaf Nodes and Routers
• A PakBus ® network consists of two to 4093 linked nodes.
• One or more leaf nodes and routers can exist in a network.