Campbell Scientific CR1000KD CR1000 Measurement and Control System - Page 350
Protocols, 4.3 Initiating Telecommunications Callback
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Section 8. Operation Digital Display external keyboard / display Direct Connect Direct Connect CS I/O Serial Comms Serial Comms 8.4.2 Protocols The CR1000 communicates with datalogger support software (p. 77) and other Campbell Scientific dataloggers (p. 563) using the PakBus (p. 461) protocol (PakBus Overview (p. 351) ). Modbus, DNP3, and Web API are also supported (see Alternate Telecommunications and Data Retrieval (p. 364) ). CAN bus is also supported when using the Campbell Scientific SDM-CAN communications module. 8.4.3 Initiating Telecommunications (Callback) Telecommunications sessions are usually initiated by a PC. Once telecommunication is established, the PC issues commands to send programs, set clocks, collect data, etc. Because data retrieval is managed by the PC, several PCs can have access to a CR1000 without disrupting the continuity of data. PakBus® allows multiple PCs to communicate with the CR1000 simultaneously when proper telecommunications networks are installed. Typically, the PC initiates telecommunications with the CR1000 via datalogger support software (p. 569). However, some applications require the CR1000 to call back the PC (initiate telecommunications). This feature is called Callback. Special features exclusive to LoggerNet (p. 569) enable the PC to receive calls from the CR1000. For example, if a fruit grower wants a frost alarm, the CR1000 can contact him by calling a PC, sending an email, text message, or page, or calling him with synthesized-voice over telephone. Callback has been utilized in applications including Ethernet, land-line telephone, digital cellular, and direct connection. Callback via telephone is well documented in CRBasic Editor Help (search term "callback"). For more information on other available Callback features, manuals for various telecommunications hardware may discuss Callback options. Contact a Campbell Scientific applications engineer for the latest information in Callback applications. Caution When using the ComME communications port with nonPakBus® protocols, incoming characters can be corrupted by concurrent use of the CS I/O for SDC communication. PakBus® communication uses a low level protocol of a pause / finish / ready sequence to stop incoming data while SDC occurs. Non-PakBus® communication includes PPP protocol, ModBus, DNP3, and generic, CRBasic-driven use of CS I/O. 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 external keyboard / display is available. When DevConfig and PakBus Graph retrieve settings, the CR1000 queries the SDC to determine what SDC devices are connected. Results 350