Inputs
There are eight (8) inputs on the ezeio hardware. More inputs can be added using the ezeio expansion modules https://ezesys.com/ezeio-mkii-i/o-expander. Other types of inputs can be added using third party devices connected via Modbus, CAN or SDI-12.
The ezeio and ezeio I/O Expander inputs are compatible with a wide variety of sensors, either directly or through the use of an amplifier or transmitter. These common, industry standard, sensor outputs are directly supported.
| Input Mode | Sensor output type | Function | Sensor examples |
| Voltage | 0-10VDC | Measuring an external voltage between 0 and 10V relative to ground (default) | pressure transducers, air quality |
| Current | 0-30mA (4-20mA) | Measuring a current, 0-30mA, typically used with 4-20mA sensors | pressure transducers, flow meters |
| Resistive | 0-500,000 Ohms | Measuring an external resistance (between the input and ground) | switches, buttons, potentiometers |
| Thermistor | Ohms to temp curve | Like Resistive, but outputting the temperature | 2.25K @ 25C, 10K @ 25C, 100K @ 25C |
| Pulse Count | Counting the number of pulses | Gas, Water, and Electric meters | |
| Pulse Rate | Hz | Measuring the frequency of pulses | Gas, Water, and Electric meters |
Settings in the ezeio's device drivers electronically configure the input to the desired mode. The drivers can also convert/scale the raw value to engineering units. For more information see the Devices section of this manual.
Input Drivers
Pulse Input driver
Do not exceed the rated voltage (10 VDC) or current (30 mA) for the inputs.
Voltage setting (0-10 VDC)
Selecting a voltage setting switches the input to high impedance mode, and the RAW input value will reflect the voltage on the input in mV (0-10000 mV). The impedance when in 0-10V mode is 69200 Ohm.
| Input setting : 0-10V | |
|---|---|
| Input range | 0 - 10240mV |
| Resolution | 2.5mV |
| Accuracy | +/- 5mV |
| Impedance | 62900 Ohm |
| Excitation | no |
Changing the range for higher voltages
If you need to monitor a higher voltage than 10V, you can connect an in-line 270kOhm resistor. This will extend the input range to 0-54.2V with a resolution of 13.24mV. We do not recommend this method for voltages exceeding 50V. For higher voltages, use a suitable voltage transducer.
Current setting (0-30mA)
When set for 0-30mA, the input will be internally connected to ground via a 200 Ohm resistor. The input scaling switches to reflect micro-Ampere though the resistor.
This mode is commonly used for industry standard 4-20mA sensors.
| Input setting : 0-30mA | |
|---|---|
| Input range | 0 - 30000µA |
| Resolution | 12.5µA |
| Accuracy | +/- 25µA |
| Impedance | 200 Ohm |
| Excitation | no |
Resistive setting (Ohms)
When the input is set to monitor an external resistance, an internal 4780 Ohm resistor is enabled to connect the input to the internal +5V. This allows a small current to run through the external resistor, and this allows the ezeio to measure the voltage and convert it to resistance.
An internal reference is used to find the ratio and more accurately calculate the external resistance in Ohms.
| Input setting : Resistance | |
|---|---|
| Input range | 0 - 1MOhm |
| Resolution | Varies over the range |
| Accuracy | Better than 2% in the 200Ohm - 100kOhm range |
| Impedance | not applicable |
| Excitation | yes, 4870 Ohm to 5V (1mA short circuit) |
Thermistor setting
A thermistor is a resistor that changes resistance with temperature. The input setting is very similar to when an external resistor is used, but the input value is recalculated using the Steinhart-Hart math to reflect a temperature.
There are five different types of thermistors supported:
| Type | Typical application | Beta |
|---|---|---|
| 10k, Type 2 | Indoor temperatures, 0°C to +60°C (30-140°F) | 3800K |
| 10k, Type 3 | Indoor temperatures, -5°C to +60°C (20-140°F) | 3500K |
| 10k | Outdoor temperatures, -25°C to +60°C (-10-140°F) | 3380K |
| 2k2 | Refrigeration systems, -40°C to +20°C (-40-70°F) | 3800K |
| 100k | Heating systems, boilers, +50°C to +150°C (120-300°F) | 4000K |
| PT1000 1) | Wide range, -70°C to +370°C (-90-700°F) (reduced resolution) | n/a |
The thermistors will continue to work outside the above temperatures, but the accuracy will be lower at higher and lower temperatures.
The PT1000 type sensor will work over a very wide temperature range, but lower resolution than a thermistor (a few °K typically).
| Input setting : Thermistor | |
|---|---|
| Input range | 20000 to 65000 (°K x100) |
| Resolution | Varies over the range |
| Accuracy | 0.5°K when around 10kOhm |
| Impedance | not applicable |
| Excitation | yes, 4870 Ohm to 5V (1mA short circuit) |
The ezeio inputs does not directly support PT100 or Thermocouple type sensors. If you need to use these types of sensors, use a signal conditioner to convert the signal to 0-10V or 4-20mA, or use a digital expander with suitable inputs.
Pulse count/frequency
When set to monitor pulses, the ezeio input can be configured either in resistive mode or in 0-10V mode. If the pulse source is a passive switch (a.k.a dry contact or potential free contact), like a KYZ output or a opto-coupler transistor output, the resistive mode is suitable and will apply enough current through the circuit for the ezeio to detect the pulses. If the pulse source is active, outputting a switched voltage, the 0-10V input mode is more suitable.
The maximum frequency that can be detected reliably by the ezeio is 400Hz.
If the pulse interval is larger than 20s (0.05Hz), the ezeio will consider this as no pulses (0 Hz).
| Input setting : Pulse | |
|---|---|
| Input range | 50-400000 mHz (mHz = Hz x 1000) |
| Resolution | |
| Accuracy | |
| Impedance | not applicable |
| Excitation | optional |
The register value has the unit mHz (Hertz x1000). To convert to other units, use these examples:
| Input | Desired output | Conversion |
|---|---|---|
| Pulses per second (Hz) | r(x,x)*0.001 |
|
| Pulses per minute (ppm) | r(x,x)*0.06 |
|
| Pulses per hour (pph) | r(x,x)*3.6 |
|
| 2L/pulse | Liters per minute | 2*r(x,x)*0.06 |
| 12 pulses per Liter | Liters per hour | 1/12*r(x,x)*3.6 |
| 14 gal/pulse | Gallons per hour | 14*r(x,x)*3.6 |
| 100 pulses per kWh | kW | 1/100*r(x,x)*3.6 |
| 0.5kWh per pulse | W | 0.5*r(x,x)*3600 |
