Table 42. CR1000 Serial Ports
Serial Port Voltage Level Logic
RS-232 (9 pin)
RS-232 Full-duplex asynchronous RS-232
CS I/O (9 pin)
TTL Full-duplex asynchronous RS-232
COM1 (C1 – C2) TTL Full-duplex asynchronous RS-232/TTL
COM2 (C3 – C4) TTL Full-duplex asynchronous RS-232/TTL
COM3 (C5 – C6) TTL Full-duplex asynchronous RS-232/TTL
COM4 (C7 – C8) TTL Full-duplex asynchronous RS-232/TTL
C1
5 Vdc SDI-12
C3
5 Vdc SDI-12
C5
5 Vdc SDI-12
C7
5 Vdc SDI-12
C1, C2, C3
5 Vdc
SDM (used with Campbell Scientific
peripherals only)
7.9.17.3 Protocols
PakBus is the protocol native to the CR1000 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 CR1000 with minimal user configuration.
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 CR1000.
Read More See SDI-12 Recording
(p. 363), SDI-12 Sensor Support (p. 267), PakBus
Overview (p. 393), DNP3 (p. 408), and Modbus (p. 411).
Many instruments require non-standard protocols to communicate with the
CR1000.
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
addressing systems that allow multiplexing of several sensors on a single
communication port, which makes for more efficient use of resources.
7.9.17.4 Glossary of Serial I/O Terms
Term. asynchronous
The transmission of data between a transmitting and a receiving device
occurs as a series of zeros and ones. For the data to be "read" correctly, the
receiving device must begin reading at the proper point in the series. In
asynchronous communication, this coordination is accomplished by having
247
To Next Page
Loading...
Need help?
General
