Communications protocols

Data loggers communicate with data logger support software LoggerNet, RTDAQ, and PC400 - these Campbell Scientific software applications include at least the following functions: data logger communications, downloading programs, clock setting, and retrieval of measurement data., other Campbell Scientific data loggers, and other hardware and software using a number of protocols including PakBus ® A proprietary communications protocol developed by Campbell Scientific to facilitate communications between Campbell Scientific devices. Similar in concept to IP (Internet Protocol), PakBus is a packet-switched network protocol with routing capabilities. A registered trademark of Campbell Scientific, Inc., Modbus Communications protocol published by Modicon in 1979 for use in programmable logic controllers (PLCs)., DNP3 Distributed Network Protocol is a set of communications protocols used between components in process automation systems. Its main use is in utilities such as electric and water companies., CPI CPI is a proprietary interface for communications between Campbell Scientific data loggers and Campbell Scientific CDM peripheral devices. It consists of a physical layer definition and a data protocol., SPI Serial Peripheral Interface - a clocked synchronous interface, used for short distance communications, generally between embedded devices., and TCP/IP Transmission Control Protocol / Internet Protocol.. Several industry-specific protocols are also supported. CAN-bus is supported when using the Campbell Scientific SDM-CAN communications module. See also Communications specifications.

Some communications services, such as satellite networks, can be expensive to send and receive information. Best practices for reducing expense include:

• Declare Public only those variables that need to be public. Other variables should be declared as Dim.

• Be conservative with use of string variables and string variable sizes. Make string variables as big as they need to be and no more. The default size, if not specified, is 24 bytes, but the minimum is 4 bytes. Declare string variables Public and sample string variables into data tables only as needed.

• When using GetVariables() / SendVariables() to send values between data loggers, put the data in an array and use one command to get the multiple values. Using one command to get 10 values from an array and swath of 10 is more efficient (requires only 1 transaction) than using 10 commands to get 10 single values (requires 10 transactions). See the CRBasic Editor help for detailed instruction information and program examples: https://help.campbellsci.com/crbasic/cr1000x/ .

• Set the data logger to be a PakBus router only as needed. When the data logger is a router, and it connects to another router like LoggerNet, it exchanges routing information with that router and, possibly (depending on your settings), with other routers in the network. Network Planner Campbell Scientific software designed to help set up datal oggers in PakBus networks so that they can communicate with each other and the LoggerNet server. For more information, see https://www.campbellsci.com/loggernet. set this appropriately when it is used. This is also set through the IsRouter setting in the Settings Editor An editor for observing and adjusting settings. Settings Editor is a feature of LoggerNet|Connect, PakBus Graph, and Device Configuration Utility.. For more information, see the Device Configuration Settings Editor Information tables and settings (advanced).

• Set PakBus beacons and verify intervals properly. For example, there is no need to verify routes every five minutes if communications are expected only every 6 hours. Network Planner will set this appropriately when it is used. This is also set through the Beacon and Verify settings in the Settings Editor. For more information, see the Device Configuration Settings Editor Beacon() and Verify() settings.

For information on Designing a PakBus network using the Network Planner tool in LoggerNet, watch the following video: https://www.campbellsci.com/videos/loggernet-software-network-planner .