Product / ZIO-20
EpiSensor’s ZIO-20 Wireless 4-20mA Current Loop Sensor interfaces with sensor products which produce a 4-20mA output. The ZIO-20 measures this current and reports the information to the Gateway. The ZIO-20 is a mains powered device and can route data from other nodes on the wireless sensor network. It interfaces to a wide variety of sensors that provide a 4-20mA current loop output.
The ZIO-20 Current Loop Sensor is particularly useful where there is an existing instrument that produces a 4-20mA signal that represents a parameter that needs to be monitored. The instrument’s current output would be dependent on the sensor type and the environmental conditions it is sensing, be it pressure, flow, temperature etc. The ZIO-20 reports data in milliamps (mA) and users can define how the milliamp values are converted to “real world” units.
The ZIO-20 must be connected to the 4-20mA current generating output and it is important that these connections are made correctly. The ZIO-20 is a mains powered device – the voltage input lead on the ZIO-20 is colour coded to conform to European CENELEC standards. The CENELEC standard insulation colours are as follows:
- L1/Live – Brown
- N – Blue
Important Note: The ZIO-20 should be connected via a switched junction box and breaker to protect the cable. Also, please ensure that the live connection is made on the same circuit as the neutral connection where residual-current devices (RCD’s) are used.
A connection diagram for the 4-20mA current loop is shown below. The polarity of the current loop connection is important.
A two core cable with suitable insulation should be threaded through the gland and connected to the terminals.
Note: If “figure of 8” or twisted pair cable is used, the waterproof seal at the gland may not be maintained.
Installation should be carried out only by personnel qualified in the installation of electrical equipment. All parts of the circuit within the enclosure must be considered to be at dangerously high mains voltage when the unit is connected to a mains voltage source.
The instrument producing the 4-20mA current loop should be configured with a time-constant of approximately 2 seconds. The ZIO-20 will poll the analogue signal every 2 seconds, average this value of the reporting interval of the node and also report the min and max values during the reporting interval time period.
Note: Averaging/min/max is a feature of v2.51 firmware or higher.
Current and Voltage limits for the current loop are as follows:
- Maximum voltage: 3V
- Maximum current: 50mA
The ZIO-20 is a passive current loop monitor. If the instrument being monitored is also passive, an external power source may be required to power the current loop.
The ZIO-20 is housed in a waterproof polycarbonate enclosure with two cable glands at the bottom for the mains supply cable and current loop input.
The ZIO-20 requires 2 screws for mounting. These screws can be preinstalled on a vertical surface spaced 120mm vertically apart. The head of the screw should be less than 8.5mm in diameter and the screw thickness should be less than 4.5mm. The screws should be left unscrewed by more than 5mm before installing the enclosure.
Once the keyhole shaped holes in the housing are placed on the screws, the screws can be tightened to secure the housing. The ZIO-20 should be mounted with the cable glands facing downwards.
Installation of the ZIO-20 should be carried out only by personnel qualified in the installation of electrical equipment. The ZIO-20 enclosure should only be opened by suitably qualified personnel when the unit has been isolated from the mains supply. All parts of the circuit within the enclosure must be considered to be at dangerously high mains voltage.
The following is a list of all sensors available on the ZIO-20. The reporting mode, reporting interval and logging enabled columns refer to the factory default settings, these settings can be configured from the Gateway.
Instantaneous 4 – 20 Milliamp Signal
Snap to Clock
Average 4-20 Milliamp level since the last report
Snap to Clock
Minimum 4-20 Milliamp level since the last report
Snap to Clock
Maximum 4-20 Milliamp level since the last report
Snap to Clock
The following table lists node specific settings for the ZIO-20 product range.
The Frequency in seconds that the system reads the 4-20mA signal to determine the average.