Campbell Scientific CR6 CR6 Measurement and Control System - Page 366

RS-232 and TTL

Page 366 highlights

Section 8. Operation communicates with SDI-12 sensors on terminals configured for SDI-12 input. See the table CR6 Terminal Definitions (p. 73) to determine those terminals configurable for SDI-12 communications. 8.1.6.2 RS-232 and TTL Read More Serial Input / Output Instructions (p. 559) and Serial I/O (p. 248). The CR6 can receive and record most TTL (0 to 5 Vdc) and true RS-232 data from devices such as smart sensors. See the table CR6 Terminal Definitions (p. 73) for those terminals and serial ports configurable for either TTL or true RS-232 communications. Use of the CS I/O port for true RS-232 communications requires use of an interface device. See the appendix CS I/O Serial Interfaces (p. 602). If additional serial inputs are required, serial input expansion modules can be connected. See the appendix Serial I/O Modules List (p. 596). Serial data are usually captured as text strings, which are then parsed (split up) as defined in the CRBasic program. Note C terminals labeled and configured as Tx transmit only 0 to 5 Vdc logic. However, C terminals labeled and configured as Rx read most true RS-232 signals. When connecting serial sensors to a C terminal configured as Rx, the sensor power consumption may increase by a few milliamps due to voltage clamps in the CR6. An external resistor may need to be added in series to the Rx line to limit the current drain, although this is not advisable at very high baud rates. Figure Circuit to Limit C Terminal RS-232 Input to 5 Volts shows a circuit that limits voltage to 5 Vdc. Figure 107. Circuit to Limit C Terminal Input to 5 Vdc 8.1.7 Field Calibration - Overview Reading List: • Field Calibration - Overview (p. 70) • Field Calibration - Details (p. 210) Calibration increases accuracy of a measurement device by adjusting its output, or the measurement of its output, to match independently verified quantities. Adjusting sensor output directly is preferred, but not always possible or practical. By adding FieldCal() or FieldCalStrain() instructions to the CR6 CRBasic program, measurements of a linear sensor can be adjusted by modifying the programmed multiplier and offset applied to the measurement. 366

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Section 8.
Operation
communicates with SDI-12 sensors on terminals configured for SDI-12 input.
See the table
CR6 Terminal Definitions
(p. 73)
to determine those terminals
configurable for SDI-12 communications.
8.1.6.2 RS-232 and TTL
Read More
Serial Input / Output Instructions
(p. 559)
and
Serial I/O
(p. 248).
The CR6 can receive and record most TTL (0 to 5 Vdc) and true RS-232 data
from devices such as smart sensors.
See the table
CR6 Terminal Definitions
(p. 73)
for those terminals and serial ports configurable for either TTL or true RS-232
communications.
Use of the
CS I/O
port for true RS-232 communications
requires use of an interface device.
See the appendix
CS I/O Serial Interfaces
(p.
602).
If additional serial inputs are required, serial input expansion modules can be
connected.
See the appendix
Serial I/O Modules List
(p. 596).
Serial data are
usually captured as text strings, which are then parsed (split up) as defined in the
CRBasic program.
Note
C terminals labeled and configured as Tx transmit only 0 to 5 Vdc logic.
However, C terminals labeled and configured as Rx read most true RS-232
signals.
When connecting serial sensors to a C terminal configured as Rx, the
sensor power consumption may increase by a few milliamps due to voltage
clamps in the CR6.
An external resistor may need to be added in series to the Rx
line to limit the current drain, although this is not advisable at very high baud
rates.
Figure Circuit to Limit C Terminal RS-232 Input to 5 Volts shows a circuit
that limits voltage to 5 Vdc.
Figure 107.
Circuit to Limit C Terminal Input to 5 Vdc
8.1.7
Field Calibration — Overview
Reading List:
Field Calibration — Overview
(p. 70)
Field Calibration — Details
(p. 210)
Calibration increases accuracy of a measurement device by adjusting its output, or
the measurement of its output, to match independently verified quantities.
Adjusting sensor output directly is preferred, but not always possible or practical.
By adding
FieldCal()
or
FieldCalStrain()
instructions to the CR6 CRBasic
program, measurements of a linear sensor can be adjusted by modifying the
programmed multiplier and offset applied to the measurement.
366