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MB4442 Fieldbus RTU

User Manual: MB4442 RTU

LED Indicators

LED

COLOUR

MEANING

IN 1 – 4

Green

Digital Input Is ON / OFF

OUT 1 – 4

Red

Output is ON

CNT 1

Blue

Flashes when the counter 1 pulses

CNT 2

Blue

Flashes when the counter 2 pulses

BUS

Green

ON Permanently to show that power is ON

Flashes OFF when unit receives a Modbus message on the rs-485 network

Electrical Connections/ Terminals

Below is the summary of the electrical connections for the MB4442 unit.

+Ve

Positive Supply Voltage 12 to 24V DC

-Ve

Negative Supply Voltage / Ground

IN1

Digital Input 1 – NPN Type (Pull to GND)

IN2

Digital Input 2 – NPN Type (Pull to GND)

IN3

Digital Input 3 – NPN Type (Pull to GND)

IN4

Digital Input 4 – NPN Type (Pull to GND)

OUT1

Digital Output 1 – NPN Type (Pull to GND)

OUT2

Digital Output 2 – NPN Type (Pull to GND)

OUT3

Digital Output 3 – NPN Type (Pull to GND)

OUT4

Digital Output 4 – NPN Type (Pull to GND)

AIN1

Analog Input 1 (4-20mA)

AIN2

Analog Input 2 (4-20mA)

AIN3

Analog Input 3 (4-20mA)

AIN4

Analog Input 4 (4-20mA)

AGND

Analog Ground for Analog Inputs

485+ (A)

RS-485 +Ve (A) (Modbus)

485-  (B)

RS-485 -Ve (B) (Modbus)

5VOUT

+5V output (for use by Pulse Counters)

CNT1

Pulse Counter 1 Input

CNT2

Pulse Counter 2 Input

Power Supply

Designed for use with a 12V or 24V DC power supply only.  Powering this device with AC power or higher voltage will cause permanent damage to the unit.

Power Requirements:

Voltage: 12V DC to 30V DC

Power Consumption: 2W

 

Powering the unit:

Wire in 12V to 30V DC into the -VE ( Negative) and +VE (Positive) terminals marked on the RTU.

Diagram

* The power supply has an internal reverse polarity protection diode.

I/O's

Digital Inputs

NPN Type

Digital Outputs

NPN Type

The internal transistor is connected to the negative power supply

The load can be supplied from the same power supply or a separate power supply which has a common negative supply connected to the negative supply of the MB4442 (common ground).

The output current is short-circuit protected for 2 seconds.

Maximum output current is 500mA continuous.

Analog Inputs

The analog inputs are referenced to the internal analog ground (AGND) for added accuracy.

If a second power supply is used for the analog inputs, it’s negative terminal must be connected to the AGND terminal of the MB4442.

The MB4442 is designed to work with a 2 wire powered loop 4-20mA signal.

Pulse Counters

Both counters have the same input circuitry

The counter increments once every time the input is connected to the -Ve power supply (GND).

The switch must be de-bounced.

The switch can be any device which connects the input to GND, such as a reed switch, optocoupler or transistor output.

RS-485 Communication

The unit’s communication works using a RS-485 serial network. It then uses the Modbus protocol on top of the RS-485 to extract the data from the units.

Connection:

The connection of the RS-485 network must be connected using a twisted pair shielded cable, where wires (A+) & (B-) are twisted around each other.

The -Ve (GND) of the unit must be common with the RS-485 master device.

Network Baud Rate

The network baud rate is set to 9600bps, 8 data bits, 1 stop bit, no parity.

Network Address:

The MB4442 is a Modbus slave device. By default, the units slave address is set to 1.  This can be changed via a specific Modbus command listed below.

Click the button below for more information on how to install and setup a fieldbus.

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