2.4.5 RS-232/CPI port
The datalogger includes one RJ45 module jack labelled RS-232/CPI. CPI is a proprietary
interface for communications between Campbell Scientific dataloggers and Campbell Scientific
CDM peripheral devices. It consists of a physical layer definition and a data protocol. CDM
devices are similar to Campbell Scientific SDM devices in concept, but the CPI bus enables
higher data-throughput rates and use of longer cables. CDM devices require more power to
operate in general than do SDM devices. CPI ports also enable networking between compatible
Campbell Scientific dataloggers. Consult the manuals for CDM modules for more information.
The CPI port has the following power levels:
l Off: Not used.
l High power: Fully active.
l Low-power standby: Whenever possible.
l Low-power bus: Sets bus and modules to low power.
When used with an RJ45-to-DB9 converter cable, the RS-232/CPI port can be used as an RS-232
port. It defaults to 115200 bps (in autobaud mode), 8 data bits, no parity, and 1 stop bit. Use
Device Configuration Utility or the SerialOpen() CRBasic instruction to change these
options.
2.5 Programmable logic control
The datalogger can control instruments and devices such as:
l Controlling cellular modem or GPS receiver to conserve power.
l Triggering a water sampler to collect a sample.
l Triggering a camera to take a picture.
l Activating an audio or visual alarm.
l Moving a head gate to regulate water flows in a canal system.
l Controlling pH dosing and aeration for water quality purposes.
l Controlling a gas analyzer to stop operation when temperature is too low.
l Controlling irrigation scheduling.
Control decisions can be based on time, an event, or a measured condition. Controlled devices
can be physically connected to C, VX, or SW12 terminals. Short Cut has provisions for simple
on/off control. Control modules and relay drivers are available to expand and augment
datalogger control capacity.
l C terminals are selectable as binary inputs, control outputs, or communication ports. These
terminals can be set low (0 Vdc) or high (3.3 or 5 Vdc) using the PortSet() or WriteIO
2. Wiring panel and terminal functions 14
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