Table of Contents

First steps

Extension

Unipi Extension are input and output extension modules for Unipi units, but also all third party controllers with RS-485 interface and Modbus RTU protocol.

In the default configuration of the device, the analog inputs and outputs are set in voltage mode and all outputs are deactivated. All DIP switches are disabled (OFF position), so that terminating resistor is not connected and SW configuration communication parameters are applied. The communication uses the Modbus RTU protocol, the table of coils and registers is available in the Downloads section.

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Attention:
Always follow the Safety instructions when handling the device.

Mounting

All units of the Unipi Extensions product line are structurally designed for mounting on a TH 35 mm DIN rail according to EN 60715.

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Warning:
Prior to mounting, make sure that the environment is disconnected from all power sources.

If the holder for DIN rail is not installed, it must be mounted first with the supplied screws (M3x5, DIN 965, PH 1) so that the spring is towards the top of the device.

DIN holder installation

To install unit on the DIN rail, slide the unit onto the rail from above (in the direction of arrow 1 in the picture below), against the spring resistance downwards and then clicking the lower part (in the direction of arrow 2 in the picture below).

Mounting on DIN rail

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Attention:
Avoid pressure on the terminals as they could be mechanically damaged.

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Caution:
Make sure that the upper edge of the DIN rail runs between the spring and the rear of the DIN holder (see figure above). Improper mounting of the DIN bracket can cause injury when mounted on the DIN rail.

Connection

Disconnectable screw terminals are used to connect the wires to the device. The purpose of each terminal contact is described on the top side of the unit case. Use the appropriate flathead screwdriver to install the wires into the terminals. Do not exceed the maximum tightening torque specified in technical parameters.

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Attention:
Always connect all cable shields (RS-485, analog sensors, etc.) on one side of the cable only, directly to the ground terminal of the cabinet/box, never to the ground point of the device.

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Warning:
Take extra care when plugging in, there is a risk of electric shock! Always ensure and check that the environment and device are disconnected from all voltage sources before starting work.

RS-485 connection

RS-485 communication line (EIA-485) is connected to the RS485 terminal contacts marked A and B. The device has an optional 120 Ω terminating resistor (terminator), marked RS485-END.

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Please note:
We recommend that you comply with the following instructions for reliable bus operation:

  • Ensure the shortest possible wiring length between devices
  • Ensure the serial topology of the bus
  • Use shielded cabling, preferably 0.8 mm diameter J-Y(ST)Y and twisted pairs, or FTP CAT6
  • Set the optimal communication speed in relation to the interference from the surrounding environment

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Configuration:
The default settings are always read when the device is (re) started. If the address selected by the DIP switches is greater than 0, the HW configuration of the communication parameters will be applied.

Power supply connection

To ensure correct operation of the device, it is necessary to first connect the 24V power supply wires to the contacts as described on the device, +24V/positive contact and GND/negative contact of the detachable screw terminal block. For information on recommended supply voltage tolerance and power consumption, refer to operating conditions and the product label.

Power supply connection

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Warning:
The device has appliance class I. To protect against electric shock and to comply with electromagnetic compatibility (EMC), it is also necessary to connect protective ground conductor to ground connector of the device marked on the case with symbol (⏚). For ground conductor connection use ring tongue and provided M4 screw with serrated lock washer.

DIN rail on which the device is installed must be connected to the main protective earth point of the cabinet/box as well.

Module operation

The reading/writing of values, incl. configuration, is done by the Modbus RTU protocol (RS-485 interface) according to the registers in Modbus table. The configuration (registers 1000-1100) allows to set e.g. the analogue input/output measurement mode or SW communication parameters.

The configuration and the current state of the outputs can be saved with coil 1003 as the default configuration, which is restored at module startup.

Quick solutions

Because deploying the Modbus protocol is not always easy or comfortable, we have ensured that all Unipi Extension device definitions are included in the most widely used Unipi controller software solutions.

Creating your own app?

If Modbus RTU communication is not possible in the selected software or is not easily deployable, you can use one of the protocols provided by Evok, which is an API interface for accessing the inputs and outputs of Unipi products. Detailed information, including documentation on installing and using the API, is available at this link.

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Please note:
An alternative or complement to Evok can also be sysfs access.

Programmable Logic Controllers (PLC)?

Units with Mervis SW are the most ideal choice. The communication with the extension module is done via the Modbus RTU protocol only and the modules can be easily connected by automatic bus search. Configuration is possible in the Mervis IDE by comfortably setting properties or module inputs/outputs and save/upload with a simple dialog.


Flow-based programming?

Node-RED OS for Unipi units has Node-RED SW pre-installed, incl. prepared nodes communicating with the Evok API via Websocket. Adding an extension module is described in Evok documentation.