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#Rocrail tutorial serial
Using the FTDI USB to Serial converter the maximum bytes you can send is limited to its internal buffer which is 60 bytes or 30 unsigned int registers. In a function 16 request the master will attempt to write to your slave and since a 9 bytes is already used for ID, FUNCTION, ADDRESS, NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write 118 bytes or 59 registers. In a function 3 request the master will attempt to read from your slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES and two BYTES CRC the master can only request 122 bytes or 61 registers. Most of the time you will connect the arduino to a master via serial using a MAX485 or similar. Note: The Arduino serial ring buffer is 128 bytes or 64 registers. The modbus_update() method updates the holdingRegs register array and checks communication. Function 5 (write single coil) is not implemented so I'm using a whole register and function 16 to set the onboard Led on the Atmega328P. 6 analogue inputs, 1 button, 1 digital output and 1 register to indicate errors encountered since started. */ #include #define ledPin 12 // onboard led #define buttonPin 7 // push button /* This example code has 9 holding registers. * * You should have received a copy of the GNU General Public License * along with this program. See the * GNU General Public License for more details. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
#Rocrail tutorial software
* * Test program for Arduino RS422/RS485 Shield * Version 1.0 * Copyright (C) 2018 Hartmut Wendt * * (based on sources of ) * * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version.