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fix polarity of DE, osci image of working example

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This commit is contained in:
Wolfgang Hottgenroth 2019-06-17 21:30:59 +01:00
parent f8fe6485d3
commit bf12960dc4
3 changed files with 4 additions and 4 deletions
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docs/modbus-really-ok.png Normal file
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6
pyserialext/writec.c
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@ -9,17 +9,17 @@ const uint8_t DE_PIN = 0;
int init() { int init() {
wiringPiSetup(); wiringPiSetup();
pinMode(DE_PIN, OUTPUT); pinMode(DE_PIN, OUTPUT);
digitalWrite(DE_PIN, HIGH); digitalWrite(DE_PIN, LOW);
} }
ssize_t writec(int fd, char *buf, size_t count) { ssize_t writec(int fd, char *buf, size_t count) {
digitalWrite(DE_PIN, LOW); digitalWrite(DE_PIN, HIGH);
ssize_t r = write(fd, buf, count); ssize_t r = write(fd, buf, count);
uint8_t lsr; uint8_t lsr;
do { do {
int r = ioctl(fd, TIOCSERGETLSR, &lsr); int r = ioctl(fd, TIOCSERGETLSR, &lsr);
} while (!(lsr & TIOCSER_TEMT)); } while (!(lsr & TIOCSER_TEMT));
digitalWrite(DE_PIN, HIGH); digitalWrite(DE_PIN, LOW);
return r; return r;
} }

2
snippets/test5.py
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@ -1,7 +1,7 @@
from pymodbus.client.sync import ModbusSerialClient from pymodbus.client.sync import ModbusSerialClient
import RS485Ext import RS485Ext
ser=RS485Ext.RS485Ext(port='/dev/ttyAMA0', baudrate=1200) ser=RS485Ext.RS485Ext(port='/dev/ttyAMA0', baudrate=1200, stopbits=2)
client = ModbusSerialClient(method='rtu') client = ModbusSerialClient(method='rtu')
client.socket = ser client.socket = ser