Digital input/output specifications
Terminals configurable for digital input and output (I/O) including status high/low, pulse width modulation, external interrupt, edge timing, switch closure pulse counting, high-frequency pulse counting, plus UART Universal Asynchronous Receiver/Transmitter for asynchronous serial communications., RS‑232 Recommended Standard 232. A loose standard defining how two computing devices can communicate with each other. The implementation of RS-232 in Campbell Scientific data loggers to computer communications is quite rigid, but transparent to most users. Features in the data logger that implement RS-232 communications with smart sensors are flexible., RS-422 Communications protocol similar to RS-485. Most RS-422 sensors will work with RS-485 protocol., RS‑485 Recommended Standard 485. A standard defining how two computing devices can communicate with each other., SDM Synchronous Device for Measurement. A processor-based peripheral device or sensor that communicates with the data logger via hardwire over a short distance using a protocol proprietary to Campbell Scientific., SDI‑12 Serial Data Interface at 1200 baud. Communications protocol for transferring data between the data logger and SDI-12 compatible smart sensors., I2C Inter-Integrated Circuit is a multi-controller, multi-peripheral, packet switched, single-ended, serial computer bus., and SPI Serial Peripheral Interface - a clocked synchronous interface, used for short distance communications, generally between embedded devices. serial-communications functions. Terminals are configurable in pairs for 5 V or 3.3 V logic for some functions.
Conflicts can occur when a control port pair is used for different instructions (TimerInput()
, PulseCount()
, SDI12Recorder()
, WaitDigTrig()
). For example, if C1 is used for SDI12Recorder()
, C2 cannot be used for TimerInput()
, PulseCount()
, or WaitDigTrig()
.
Terminals: C1-C8
Sustained Logic Input Voltage without Damage:
Logic Levels and Drive Current:
Terminal pair configuration | 5 V source |
3.3 V source |
---|---|---|
Logic low | ≤ 1.5 V | ≤ 0.8 V |
Logic high | ≥ 3.5 V | ≥ 2.5 V |
C1 - C8 | 10 mA @ 3.5V | 10 mA @ 1.85V |
Switch closure input
Terminals: C1-C8, P1-P2
Pull-Up Resistance: 100 kΩ to 5 V
Event: Low (<0.8 V) to High (>2.5 V)
Maximum Input Frequency: 150 Hz
Minimum Switch Closed Time: 5 ms
Minimum Switch Open Time: 6 ms
Maximum Bounce Time: 1 ms open without being counted
High-frequency input
Terminals: C1-C8, P1-P2
Pull-Up Resistance: 100 kΩ to 5 V
Event: Low (<0.8 V) to High (>2.5 V)
Maximum Input Frequency:
Edge timing
Terminals: C1-C8
Maximum Input Frequency: ≤ 1 kHz
Resolution: 500 ns
Edge counting
Terminals: C1-C8
Maximum Input Frequency: ≤ 2.3 kHz
Quadrature input
Terminals:
Maximum Frequency: 2.5 kHz
Minimum Pulse Width: 10 µs
Pulse-width modulation
Terminals: C1-C8
Maximum Period: 36.4 seconds
Resolution:
- 0 – 5 ms: 83.33 ns
- 5 – 325 ms: 5.33 µs
- > 325 ms: 31.25 µs
See also Pulse measurements and Pulse measurement specifications.