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Implementation of the Modbus protocol in Java language
package com.invertor.modbus.net.stream;
import com.invertor.modbus.Modbus;
import com.invertor.modbus.exception.ModbusChecksumException;
import com.invertor.modbus.serial.SerialPort;
import com.invertor.modbus.utils.DataUtils;
import java.io.IOException;
/*
* Copyright (C) 2016 "Invertor" Factory", JSC
* [http://www.sbp-invertor.ru]
*
* This file is part of JLibModbus.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Authors: Vladislav Y. Kochedykov, software engineer.
* email: [email protected]
*/
public class InputStreamASCII extends InputStreamSerial {
private int lrc = 0;
public InputStreamASCII(SerialPort serial) {
super(serial);
}
private void lrcAdd(byte b) {
lrc += b;
}
private int lrcGet() {
return (byte) -lrc;
}
@Override
public void frameCheck() throws IOException, ModbusChecksumException {
int cr;
int lf;
int r_lrc;
r_lrc = (byte) read();
int c_lrc = (byte) lrcGet();
cr = readRaw();
lf = readRaw();
// following checks delimiter has read (LF character by default)
if (cr != Modbus.ASCII_CODE_CR || lf != Modbus.getAsciiMsgDelimiter())
Modbus.log().warning("\\r\\n not received.");
if (c_lrc != 0 || r_lrc == 0) {
throw new ModbusChecksumException(r_lrc, c_lrc);
}
}
@Override
public void frameInit() throws IOException {
lrc = 0;
char c = (char) readRaw();
if (c != Modbus.ASCII_CODE_COLON) {
throw new IOException("no bytes read");
}
}
public int readRaw() throws IOException {
return super.read();
}
@Override
public int read() throws IOException {
int b;
char c = (char) readRaw();
b = DataUtils.fromAscii(c, (char) readRaw());
lrcAdd((byte) b);
return b;
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
for (int i = off; i < len; i++) {
b[i] = (byte) read();
}
return len;
}
}