BARIX X8

I/O to RS-485 Modbus converter for commercial interfacing, control and home automation applications

The BARIX X8 is an I/O to RS-485 Modbus converter for commercial interfacing, control and home automation applications.

Using the industry standard Modbus protocol over 2-wire RS-485 the device can be controlled from any Modbus capable master.

Eight independent configurable inputs/outputs allow the use of the BARIX X8 in a wide range of I/O applications:

• General I/O to RS-485 converter (inputs and outputs)
• Up to 8 push buttons (inputs) or LED’s for status display
• Local analog voltage reading (0-5VDC, 8 inputs)
• Local temperature (up to 8 Barix TS digital sensors)
• WIEGAND reader to RS-485 converter (2 inputs for D0 and D1, other 6 I/Os usable with standard functions)

The device is configured via the serial interface using standard Modbus read/writes. If the device ID is unknown, a special command is available, which can be sent via broadcast and uses the serial number of the device to send it new configuration info.

If the address of the device is not known, it can be reset to default parameters (see chapter “Configuration”).

The supported protocol is Modbus/RTU at 19200 (default) and 9600 Baud, with even (default) or no parity.

Hardware

Case
The BARIX X8 I/O to RS-485 Modbus converter comes in an open plastic case. Two mounting brackets with 5mm holes allow mounting on surfaces but can be cut off (predetermined cut line) if not used.

Connectors
The Power/RS-485, I/O (I/O, 5Vout,GND) and cable shield are available on 3 spring contact connector blocks for wires AWG28 - AWG16 / 0.08 - 1.3 mm2

Power supply requirements
The BARIX X8 is equipped with an universal power input and accepts both AC and DC voltage. The AC supply range is 12 to 24 Volts and 9 to 30 Volts when powered by a DC power supply.
A voltage regulator controls the internally needed operating voltage of 5VDC. The BARIX X8 consumes with all outputs activated 1 Watt max. The BARIX X8 is reverse polarity protected.
Attention: When powering the BARIX X8 and other BARIX devices (Barionet, IO12, R6), connected over RS-485, using a single power supply only a DC type power supply can be used as the RS-485 interfaces are not completely potential free.

Inputs
All I/O pins are directly connected to the CPU and the absolute rating is TTL level (0 to 5VDC). When used as digital input the signal is filtered (48 milliseconds period for debouncing) to allow for direct connection of buttons or contact closures.

The analog value of each input is digitalized every 16 milliseconds (sampling rate 62.5 Hz) with a resolution of 10bit (0 to 1023) and is stored in separate Modbus registers.

On each input a BARIX TS digital temperature sensor can be attached for precise temperature reading.

Outputs
All I/O pins are connected to the CPU directly and the absolute rating is TTL level (0..5VDC). Each output can sink or source up to 20mA. See “5VDC output” for total current limitations !

5VDC output
A regulated 5VDC output is available to provide power to small devices, LEDs etc. To prevent overheating of the voltage regulator the sourcing current of 5VDC and all used outputs combined should not exceed 24mA @ 30VDC Vin, 32mA @ 24VDC Vin, 85mA @ 12VDC Vin or 100mA@ Vin <= 11VDC.

RS-485
The BARIX X8 has an RS-485 host interface, available on a spring contact connector block. Besides “A” and “B” signals for the differential, bidirectional bus signal, a third connection is available, commonly referred to as “reference ground”. This signal is internally tied to signal ground via a 100 Ohm series resistor.

Termination resistors are NOT provided on-board. A termination resistor may be added at each end of the RS485 bus if required.

The BARIX X8, as well as other Barix I/O extension units, feature soft pull-up (B) and pull down (A) 10kOhm resistors, which force the inactive bus to a relatively high impedance, idle condition.

Both A and B line signals are heavily protected against ESD (Electrostatic Discharge).

Supported interface configurations are:
19200 baud, 8bit, even parity, 1 stop bit (**default**)
19200 baud, 8bit, no parity, 1 stop bit
9600 baud, 8bit, even parity, 1 stop bit
9600 baud, 8bit, no parity, 1 stop bit

LED Indicators
4 LED indicators on the unit show the conditions CPU heartbeat as well as RS-485 receive and transmit activity.

Configuration Memory
The BARIX X8 contains 256 bytes of non volatile configuration memory (EEPROM) which can be read and (most of it) written via standard Modbus commands.