Definition
serial_read(ser, length=-1, timeout=-1)
Features
This function reads the data from a serial port.
Parameters
|
Parameter Name |
Data Type |
Default Value |
Description |
|---|---|---|---|
|
ser |
serial.Serial |
- |
Serial instance |
|
length |
int |
-1 |
Number of bytes to read
|
|
timeout |
int float |
-1 |
Read waiting time
|
Return
|
Value(res, rx_data) |
Description |
|
|
res |
n |
Number of bytes of the received data |
|
-1 |
The port is not open. |
|
|
-2 |
serial.SerialException error occurred |
|
|
rx_data |
Number of bytes read (byte type) |
|
Exception
|
Exception |
Description |
|---|---|
|
DR_Error (DR_ERROR_TYPE) |
Parameter data type error occurred |
|
DR_Error (DR_ERROR_VALUE) |
Parameter value is invalid |
Example
Python
ser = serial_open(port="COM", baudrate=115200, bytesize=DR_EIGHTBITS,
parity=DR_PARITY_NONE, stopbits=DR_STOPBITS_ONE)
res, rx_data = serial_read(ser)
#Wait indefinitely until data is received
res, rx_data = serial_read(ser, timeout=3)
#Wait until data is received, set a 3 seconds timeout
# If received within 3 seconds, the read data is returned immediately
# Return the value read so far after 3 seconds have elapsed
res, rx_data = serial_read(ser, length=100)
# Wait indefinitely until reading 100 bytes
res, rx_data = serial_read(ser, length=100, timeout=3)
#Wait until reading 100byte, set 3 seconds timeout
# If 100 bytes are received within 3 seconds, the read data is returned immediately.
# Return the value read so far after 3 seconds have elapsed
# Convert the received byte type to string type
rx_msg = rx_data.decode()
# rx_data is a byte type and decode() is used to convert it to a string type.
# For example, if rx_data = b”abcd”, then rx_msg=”abcd”.
res, rx_data = serial_close(ser)
Keyword
serial_ / read