Campbell Scientific CR6 CR6 Measurement and Control System - Page 86
Alternate Telecommunications - Overview
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Section 5. System Overview 5.2.9.5 Data-File Formats in CR6 Memory Routine CR6 operations store data in binary data tables. However, when the TableFile() instruction is used, data are also stored in one of several formats in discrete text files in internal or external memory. See Data Storage - On-board (p. 376) for more information on the use of the TableFile() instruction. 5.2.9.6 Data Format on Computer CR6 data stored on a PC with datalogger support software (p. 604) are formatted as either ASCII or binary depending on the file type selected in the support software. Consult the software manual for details on available data-file formats. 5.2.10 Alternate Telecommunications - Overview Reading List: • Alternate Telecommunications - Overview (p. 86) • Alternate Telecommunications - Details (p. 409) The CR6 communicates with external devices to receive programs, send data, or act in concert with a network. The primary communication protocol is PakBus (p. 503). Other telecommunication protocols are supported, including Web API (p. 418), Modbus (p. 413), and DNP3 (p. 409). Refer to the section Specifications (p. 91) for a complete list of supported protocols. The appendix Data Retrieval and Telecommunications - Peripherals Lists (p. 601) lists peripheral communication devices available from Campbell Scientific. Keyboard displays also communicate with the CR6. See Keyboard Display - Overview (p. 79) for more information. 5.2.10.1 Modbus Reading List: • Modbus - Overview (p. 86) • Modbus - Details (p. 413) The CR6 supports Modbus master and Modbus slave communications for inclusion in Modbus SCADA networks. Modbus is a widely used SCADA communication protocol that facilitates exchange of information and data between computers / HMI software, instruments (RTUs) and Modbus-compatible sensors. The CR6 communicates with Modbus over RS-232, RS-485, and TCP. Modbus systems consist of a master (PC), RTU / PLC slaves, field instruments (sensors), and the communication-network hardware. The communication port, baud rate, data bits, stop bits, and parity are set in the Modbus driver of the master and / or the slaves. The Modbus standard has two communication modes, RTU and ASCII. However, CR6s communicate in RTU mode exclusively. Field instruments can be queried by the CR6. Because Modbus has a set command structure, programming the CR6 to get data from field instruments is much simpler than from serial sensors. Because Modbus uses a common bus and addresses each node, field instruments are effectively multiplexed to a CR6 without additional hardware. 86