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Unipi Extension xS50


Unipi Extension xS50 is an extension module for Unipi Neuron and Unipi Patron programmable logic controllers. The module allows for a quick extension of automation networks by additional I/Os. The xS50 is the most versatile module of the xS line, combining digital inputs, relay outputs and analogue I/Os.

Note: The xS10 was phased out of production. The product was replaced by the Extension xS51.


Product description

The UniPi Extension line of extension modules was designed as a quick and inexpensive way to extend the automation network by additional inputs/outputs without the need to purchase another PLC. Modules are not equipped with a computing module, which is replaced by an additional I/O board. Computing module is represented by a master PLC to which the module is connected via RS485 serial interface.

The xS50 is a universal module featuring a combination of digital inputs, relay outputs and a set of multiple analogue I/Os. Analogue inputs can be used to read voltage, current or resistance to collect data from various analogue sensors (thermometers, pressure meters, tensometers etc.). Analogue outputs are suitable for controlling multi-state devices (electric motors, three-way valves, heat exchangers) via 0-10V DC voltage.

Basic features

Digital inputs 6 Common features
RS485 serial interface (Modbus RTU)
Aluminium chassis (IP20)
Power supply: 24V DC, 0.63/1.5A
Relay outputs 5
Analogue inputs* 4
Analogue outputs* 4
RS485 serial interface 1

*more detailed info about the number and type of analogue I/Os is available in the product's datasheet (see the Files tab above)

Inputs & outputs description

Digital inputs (DI) are designed to read binary logic states represented by direct voltage levels. That makes them suitable for reading data from various binary sensors and devices such as switches (on/off), motion sensors (movement detected/not detected), liquid level sensors (full tank/empty tank) etc. All digital inputs also feature counter functionality by default.

Relay outputs (RO) are primarily used for switching two-state devices with higher current draw such as lightbulbs, thermoelectric valve drives, water heaters, pumps etc.

Analogue inputs (AI) are designed to measure voltage, current or resistance to read values from various analogue sensors such as thermometers, pressure meters, tensometers etc.

Analogue outputs (AO) serve for control of multi-state external devices through direct voltage or current and is suitable for control and regulation of devices such as three-way valves, heat exchangers, electric motors etc. 

Communication interfaces

Extension modules communicate through the RS485 interface (Modbus protocol). Connection manual for extension modules can be found on this link

Additional functionality

Along with standard I/O functionality, the module offers several functions to enhance the module's performance and to allow it to react to critical events.

Digital inputs feature Direct Switch functions allowing for connecting digital inputs with relay outputs. Direct Switch can be configured for one of three modes: Copy (switching output by active input), Invert (output is switched by inactive input) and Toggle (output is switched by each input change). Direct Switch is independent of the control software and is thus suitable for applications demanding a lowest possible response time (such as lighting control).

The default setting is a function allowing each processor to save its default configuration. This configuration is loaded after every device reboot triggered either by a manual restart or by a power outage.

MasterWatchdog feature monitors the communication between CPU and I/O board processors. If no exchange occurs within a pre-set timeframe, the MasterWatchdog automatically resets the device and me/O modules back into default settings.

I/O boards of the module feature their own control processor, which retains the basic I/O functionality in the case of PLC downtime or connection failure.

Device addressing and DIP switch setting

Addressing the extension module can be done either via control software running on the remote master control unit or can be set manually via the integrated DIP switch. The DIP switch allows the user to set up to 4 bits of address and is evaluated in preference to software settings. If the address on DIP switch is set to “0000”, all DIP switch settings are ignored and the software settings take priority.

Package contents

  • extension module
  • removable screw terminals
  • DIN rail holder (35 mm)
  • 3× DIN rail holder mounting screws
  • 1× grounding screw

Extension modules overview

Name DI DO RO AI AO RS485 Common features
Extension modules,the size on DIN rail: 4 modules = 7 cm
xS10 16 - 8 - - 1

Extension modules communicate with controllers via the Modbus RTU protocol and can be connected to a controller using the RS485 serial interface. Modules are compatible with both Neuron and Patron controllers and can be also used with any other Modbus-compatible PLC.

xS30 24 - - - - 1
xS40 8 - 14 - - 1
xS50 6 - 5 4 4 1


Modbus register map
Table overview of Modbus registers
Declaration of conformity
Product datasheet
Product features and technical information

Digital inputs 6
Relay outputs 5
Analog inputs 4
Analog outputs 4
RS485 interface Yes
Power 24 V DC
Dimensions 90 × 70 × 60 mm
Mounting DIN rail (35 mm)
Weigth 310 g
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