Description

The core of the Kappa4310Ard Modbus Shield is the IS4310 I2C Modbus RTU Server chip, which is connected to an RS485 transceiver. This transceiver interfaces with the daisy-chained RJ45 connectors. Since the connectors are daisy-chained, they are functionally identical—connecting the Modbus master to either one makes no difference.

The IS4310 I2C-Serial Interface connects to the I2C pins of the shield. The shield includes a jumper that allows selection of the I2C pull-up voltage: 5V, 3.3V, or Floating. The Floating option is useful when the pull-up resistors are located outside the Kappa4310Ard.

It is crucial to ensure that pull-up resistors are present either on the shield or elsewhere in the circuit. Without pull-up resistors, the I2C-Serial Interface will not function.

Since the IS4310 is 5V tolerant, it can operate with I2C pull-up voltages of 5V and with transceivers powered at 5V. Using 5V transceivers provides better noise immunity and allows for longer bus distances.

The Shield has 3 LEDs. The Rx yellow LED will blink on received data, and Tx yellow LED will blink on the IS4310 answer. The Power green LED will indicate that the board has detected power. Please note that the board requires both 3.3V and 5V to operate.

A potentiometer is placed on the board to provide a software variable that can be easily adjusted. By reading the analog value of the potentiometer and storing it in a Holding Register, you can continuously monitor the changes on the Modbus Master in real time as you adjust the potentiometer's position. This is a typical application for Modbus sensor development. The output voltage of the potentiometer ranges from 0V to 3.3V.

To develop an actuator, an RGB LED is placed on the board to display the state of Modbus Holding Registers. For example, you can create a traffic light simulation: write a program that reads values from three Holding Registers and adjusts the PWM of each LED accordingly. This is a typical application for Modbus actuator development.