Analog inputs
Extension
If you are looking for information on the Extension xS51, please see Analog inputs - type 1
Analog inputs type 2 are available in the Extension xS52, xS53 and xS54. To measure voltage or current, the negative pole of the external device being measured is connected to the AGND terminal of the connector and its positive pole (signal) to the AIx (or AIy.x) terminal. When measuring resistance, polarity does not matter and one connector is always reserved for one sensor.
Please note:
For devices that support voltage measurement, this mode is factory set as default to avoid possible damage.
Attention:
Before connecting the measured device, it is necessary to check the measurement settings first by the prefered software and according to the type of connected device - see measurement description below.
Connection
The following images illustrate the connection and measurement of the voltage and current source to the AI and AGND terminals.
Voltage measurement
Current measurement
Connection of resistive sensors to analog inputs is realized by two-wire method. The terminal names are different for some Extension model, but the wiring is identical.
Extension xS54
Extension xS52
Mode description
Analog inputs on the Extension xS52, xS53 and xS54 support current, voltage and resistance measurements. The selected measurement mode must first be set in the control software. For voltage and resistance measurement modes, two precision modes are available. The read value is of data type float32 (real) and corresponds to the measured value at the input (V DC, mA, Ω).
This analog input supports the following modes:
- Voltage 0–10 V DC
- Voltage 0–2 V DC
- Current 4–20 mA
- Resistance 75–2000 Ω
- Resistance 1–20 kΩ
| Extension | Voltage | Current | Resistance |
|---|---|---|---|
| xS52 | ☑ | ||
| xS53 | ☑ | ☑ | |
| xS54 | ☑ | ☑ | ☑ |
Mode setting and input reading
Method of setting the measurement mode depends on the software used:
- Mervis: instructions for configuring the analog input measurement mode can be found at this link
- Evok (Node-RED): the measurement mode configuration is available within the “analog input” device and its “mode” property, see the Evok documentation for more information
- Modbus: if the Evok cannot be used, or if Modbus communication is preferred, it is also possible to configure the analog I/O measurement mode by writing directly to the registers (1000-1100) according to the Modbus table
Reading depends on the software used:
- Mervis: see guide Connecting to Unipi extension
- Evok: see the Evok documentation
- Node-RED: using prepared nodes communicating with the Evok API via Websocket
- Modbus: reading and writing registers according to the Modbus table (registers 0-100)
Special functions
Aside from the standard inputs and outputs, Unipi Extension modules also feature additional functions for broadening the possible applications, performance optimization and monitoring of the entire project. These functions are calculated directly by the Extension's microprocessor and are thus independent on the control software.
Here you can find more information and tutorials about special functions for:
Default configuration
This function is used to save the current configuration of the section (extension module) into its memory. In the case of power cycle of the device or reboot of the section (extension module), the stored configuration is loaded and applied. This functionality is also known as “copy
running-config to startup-config”.
| Stored data | Default configuration |
|---|---|
| Measurement mode | voltage measurement (on xS52 resistance measurement up to 2 kΩ) |
Master Watchdog
This function runs on the section's (extension module's) microprocessor and continuously monitor the commands from the application running on the unit. If no commands are detected within a configured time (MWD Timeout), the section's (extension module's) processor automatically reboots and reverts to the default configuration described above. This function ensures a safe configuration is set in case of emergency situations (unit failure, communication error or software issues) to prevent damage to controlled devices or any hazards to personnel.
Technical parameters
| Input terminals | AI / AIS |
| Common ground | AGND / AIR |
| Overvoltage protection | Integrated transil |
| Maximum voltage | 15 V⎓ |
| Maximum current | 40 mA |
| Connection | SINK (measurement relative to the ground) |
| Galvanic isolation (pulse) | 1500 V between AI and all other circuits |
Attention:
Measurements outside the specified range may reduce the accuracy of the measurement and/or reduce the input impedance.
In case of strong interference to the cable (EN 6100-6-4), the measurement accuracy can be reduced to 1 % of the measured value. The use of additional EMC filters and shielded cabling is recommended (connect shield to the ground point of the device).
Voltage 0-10 V
| Available on device | xS53, xS54 |
| Measuring range | 0.1–10 V |
| Accuracy | ±0.2 % (of range) |
| Input resistance | 12 kΩ ±20 % |
| Resolution | 24 bits |
| Conversion time | 200 ms |
Voltage 0-2 V
| Available on device | xS53, xS54 |
| Measuring range | 0.1–2 V |
| Accuracy | ±1 % (of range) |
| Input resistance | 1 MΩ ±50 % |
| Resolution | 24 bits |
| Conversion time | 200 ms |
Current 4-20 mA
| Available on device | xS53, xS54 |
| Measuring range | 1–20 mA |
| Accuracy | ±0.2 % (of range) |
| Input resistance | 100 Ω ±1 % |
| Resolution | 24 bitů |
| Conversion time | 200 ms |
Resistance 2 kΩ
| Available on device | xS52, xS54 |
| Measuring range | 75–2000 Ω |
| Connection | Two-wire |
| Measuring current | < 0.3 mA (average) |
| Resolution | 24 bits |
| Accuracy | ±0.3 % (of value) / 0.5 Ω |
| Conversion time | 200 ms |
| Compatible sensors | Pt100/Pt1000 (tol. ±0.75 ˚C), Ni100/Ni1000/2k reostat, etc.. |
Please note:
The compensation of the lead resistance and the conversion to temperature according to the selected sensor is up to the user application.
Resistance 20 kΩ
| Available on device | xS52, xS54 |
| Measuring range | 1–20 kΩ |
| Connection | Two-wire |
| Measuring current | < 0.03 mA (average) |
| Resolution | 24 bits |
| Accuracy | ±1 % (of value) / 10 Ω |
| Conversion time | 200 ms |
| Compatible sensors | Reostat |
