MB4442 Fieldbus RTU
User Manual: MB4442 RTU
IN 1 – 4
Digital Input Is ON / OFF
OUT 1 – 4
Output is ON
Flashes when the counter 1 pulses
Flashes when the counter 2 pulses
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.
Positive Supply Voltage 12 to 24V DC
Negative Supply Voltage / Ground
Digital Input 1 – NPN Type (Pull to GND)
Digital Input 2 – NPN Type (Pull to GND)
Digital Input 3 – NPN Type (Pull to GND)
Digital Input 4 – NPN Type (Pull to GND)
Digital Output 1 – NPN Type (Pull to GND)
Digital Output 2 – NPN Type (Pull to GND)
Digital Output 3 – NPN Type (Pull to GND)
Digital Output 4 – NPN Type (Pull to GND)
Analog Input 1 (4-20mA)
Analog Input 2 (4-20mA)
Analog Input 3 (4-20mA)
Analog Input 4 (4-20mA)
Analog Ground for Analog Inputs
RS-485 +Ve (A) (Modbus)
RS-485 -Ve (B) (Modbus)
+5V output (for use by Pulse Counters)
Pulse Counter 1 Input
Pulse Counter 2 Input
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.
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.
* The power supply has an internal reverse polarity protection diode.
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.
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.
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.
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.
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.
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.