Communications ports
The data logger is equipped with ports that allow communications with other devices and networks, such as:
- Computers
- Smart sensors
Modbus Communications protocol published by Modicon in 1979 for use in programmable logic controllers (PLCs). and DNP3 outstation 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. networks- Modems
- Campbell Scientific 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.® networks
- Other Campbell Scientific data loggers
Campbell Scientific data logger communications ports include:
- RS-232 Recommended Standard 232. A loose standard defining how two computing devices can communicate with each other. The implementation of RS-232 in Campbell Scientific data loggers to computer communications is quite rigid, but transparent to most users. Features in the data logger that implement RS-232 communications with smart sensors are flexible.
- USB Device
- USB Host
- C terminals
- COM ports (TX and RX)
USB device port
The USB device port supports communicating with a computer through 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. or through virtual Ethernet (RNDIS Remote Network Driver Interface Specification - a Microsoft protocol that provides a virtual Ethernet link via USB.), and provides 5 VDC power to the data logger (powering through the USB port has limitations - details are available in the specifications). Although the USB connection supplies 5 V power, a 12 VDC battery will be needed for field deployment.
CR350 data loggers have a single USB port that acts as both a device and host.
USB host port
USB host provides portable data storage on a USB thumb drive. A FAT32-formatted USB thumb drive can be inserted into the host port and will show up as a drive (USB:) in file-related operations. Measurement data is stored on USB: as discrete files by using the TableFile() instruction. Files on USB: can be collected by inserting the thumb drive into a computer and copying the files.
USB: can be used in all CRBasic file-access-related instructions. Because of data reliability concerns in non-industrial rated drives, this drive is not intended for long-term unattended data storage. Rather, configure Tablefile() for milking (plug-and-pull) to periodically collect data. Files on USB: are not affected by program recompilation or formatting of other drives.
See the CRBasic Editor help for detailed instruction information and program examples:
C and COM terminals for communications
C terminals are configurable for the following communications types:
- SDI-12
- RS-232
- TTL (0 to 5 V)
Some communications types require more than one terminal, and some are only available on specific terminals. See Communications specifications for more information.
SDI-12 ports
SDI-12 Serial Data Interface at 1200 baud. Communications protocol for transferring data between the data logger and SDI-12 compatible smart sensors. is a 1200 baud protocol that supports many smart sensors.
For more information, see SDI-12 communications.
RS-232, RS-422, RS-485, TTL ports
RS-232, RS-422, RS-485, TTL communications are typically used for the following:
- Reading sensors with serial output
- Creating a multi-drop network
- Communications with other data loggers or devices over long cables
The maximum cable length for RS-232 communication is typically limited to 50 feet (15 meters) at 19200 baud. Higher baud rates may result in shorter transmission distances due to signal degradation.
RS-485 supports a theoretical maximum point-to-point communication distance of 1200 meters (4000 feet). To achieve this distance, it's essential to use well-shielded and insulated cable, ensure careful installation, apply bus termination, and maintain low data rates (baud) of less than 115200 bps.
Configure Device Configuration Utility Software tool used to set up data loggers and peripherals, and to configure PakBus settings before those devices are deployed in the field and/or added to networks. Also called DevConfig. or by using the SerialOpen() CRBasic instruction. Terminals are configured in pairs for TTL, RS-232, and half-duplex RS-422 and RS-485 communications. For full-duplex RS-422 and RS-485, four terminals are required. See also Communications protocols.
RS-232 ports are not isolated.
See also Communications specifications.