Campbell Scientific CR1000KD CR800 and CR850 Measurement and Control Systems - Page 335

Section 8. Operation 8.5.1 PakBus Addresses CR800s 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. 336) , 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, CR800 Status table, or with an external 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. • Leaf nodes are measurement devices at the end of a branch of the PakBus® web. o Leaf nodes can be linked to any router. o A leaf node cannot route packets but can originate or receive them. • Routers are measurement or telecommunications devices that route packets to other linked routers or leaf nodes. o Routers can be branch routers. Branch routers only know as neighbors central routers, routers in route to central routers, and routers one level outward in the network. o Routers can be central routers. Central routers know the entire network. A PC running LoggerNet is typically a central router. o Routers can be router-capable dataloggers or communications devices. The CR800 is a leaf node by factory default. It can be configured as a router by setting IsRouter in its Status table to 1 or True. The network shown in figure PakBus Network Addressing (p. 336) contains six routers and eight leaf nodes. 8.5.2.1 Router and Leaf-Node Configuration Consult the appendix Router and Leaf-Node Hardware for a table of available PakBus® leaf-node and router devices. 335