Campbell Scientific CR1000KD CR800 and CR850 Measurement and Control Systems - Page 203
I/O Ports, 8.8.3 Protocols
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Section 7. Installation 7.8.8.2 I/O Ports 7.8.8.3 Protocols The CR800 supports two-way serial communication with other instruments through ports listed in table CR800 Serial Ports (p. 203). A serial device will often be supplied with a nine-pin D-type connector serial port. Check the manufacture's pinout for specific information. In most cases, the standard nine-pin RS-232 scheme is used. If that is the case then, • Connect sensor RX (receive, pin 2) to datalogger Tx (transmit, channel C1, C3). • Connect sensor TX (transmit, pin 3) to datalogger Rx (receive, channel C2, C4). • Connect sensor ground (pin 5) to datalogger ground (G terminal) Note Rx and Tx lines on nine-pin connectors are sometimes switched by the manufacturer. Table 31. CR800 Serial Ports Serial Port Voltage Level RS-232 (9-pin) RS-232 CS I/O (9-pin) TTL COM1 (C1 - C2) TTL COM2 (C3 - C4) TTL C1 5 VDC C3 5 VDC C1, C2, C3 5 VDC Logic Full-duplex asynchronous RS-232 Full-duplex asynchronous RS-232 Full-duplex asynchronous RS-232/TTL Full-duplex asynchronous RS-232/TTL SDI-12 SDI-12 SDM (used with Campbell Scientific peripherals only) PakBus is the protocol native to the CR800 and transparently handles routine point-to-point and network communications among PCs and Campbell Scientific dataloggers. Modbus and DNP3 are industry-standard networking SCADA protocols that optionally operate in the CR800 with minimal configuration by the user. PakBus®, Modbus, and DNP3 operate on the RS-232, CS I/O, and four COM ports. SDI-12 is a protocol used by some smart sensors that requires minimal configuration on the CR800. Read More! See SDI-12 Recording (p. 308), SDI-12 Sensor Support (p. 173), PakBus Overview (p. 334), DNP3 (p. 347), and Modbus (p. 350). Many instruments require non-standard protocols to communicate with the CR800. Note If an instrument or sensor optionally supports SDI-12, Modbus, or DNP3, consider using these protocols before programming a custom protocol. These higher-level protocols are standardized among many manufacturers and are easy to use, relative to a custom protocol. SDI-12, Modbus, and DNP3 also support 203