Section 8. Operation
525
API commands are also used with Campbell Scientific’s RTMC web server
datalogger support software
(p. 97).
Look for the API commands in
CRBasic
Editor Help
.
8.10.2 DNP3 — Details
Related Topics:
•
DNP3 — Overview
(p. 89)
•
DNP3 — Details
(p. 525)
See the technical paper
DNP3 with Campbell Scientific Datalogger
, which is
available at https://www.campbellsci.com/app-notes.
8.10.3 Modbus — Details
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 CR6 supports RTU and ASCII communication modes on
RS-232 and RS485 connections. It exclusively uses the TCP mode on IP
connections.
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.
A CR6 goes into sleep mode after 40 seconds of communication inactivity. Once
asleep, two packets are required before the CR6 will respond. The first packet
awakens the CR6; the second packet is received as data. This would make a
Modbus master fail to poll the CR6, if not using retries. The CR6, through
DevConfig
or the
Status
table (see
Info Tables and Settings
(p. 613))
, can be set to
keep communication ports open and awake, but at higher power usage.
8.10.3.1 Modbus Terminology
Table
Modbus to Campbell Scientific Equivalents
(p. 525)
lists terminology
equivalents to aid in understanding how CR6s fit into a SCADA system.
Summary of Contents for CR6 Series
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Page 76: ...Section 5 Overview 76 FIGURE 20 Half Bridge Wiring Example Wind Vane Potentiometer ...
Page 80: ...Section 5 Overview 80 FIGURE 23 Pulse Input Wiring Example Anemometer ...
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Page 454: ...Section 8 Operation 454 FIGURE 104 Narrow Sweep High Noise ...
Page 459: ...Section 8 Operation 459 FIGURE 106 Vibrating Wire Sensor Calibration Report ...
Page 535: ...Section 8 Operation 535 8 11 2 Data Display FIGURE 121 CR1000KD Displaying Data ...
Page 537: ...Section 8 Operation 537 FIGURE 123 CR1000KD Real Time Custom ...
Page 538: ...Section 8 Operation 538 8 11 2 3 Final Storage Data FIGURE 124 CR1000KD Final Storage Data ...
Page 539: ...Section 8 Operation 539 8 11 3 Run Stop Program FIGURE 125 CR1000KD Run Stop Program ...
Page 541: ...Section 8 Operation 541 FIGURE 127 CR1000KD File Edit ...
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Page 610: ...Section 11 Glossary 610 FIGURE 137 Relationships of Accuracy Precision and Resolution ...
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