Campbell Scientific CR3000 CR3000 Micrologger - Page 356

Section 8. Operation 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. 356