cheap_modbus_rtu
Lightweight control of cheap Modbus RTU components using Python
Public Member Functions | Public Attributes | Static Public Attributes | List of all members
cheap_modbus_rtu.cheap_modbus_io.PWM8A04 Class Reference

Control PWM8A04 3-channel PWM output modules via RS-485 Modbus RTU. More...

Public Member Functions

def __init__ (self, int slave_id=1, str serial_device_name=None, int baudrate=9600, **kwargs)
 
int get_output_frequency (self, int output_no)
 Return the current frequency setpoint for output. More...
 
def set_output_frequency (self, int output_no, int frequency)
 Set frequency for PWM output. More...
 
int get_output_duty (self, int output_no)
 Return the current PWM duty cycle setpoint value for output. More...
 
def set_output_duty (self, int output_no, int duty)
 Set PWM duty cycle for output (high-active) More...
 
int get_slave_id (self)
 Sends a broadcast query to all devices on the bus. More...
 
def set_slave_id (self, int slave_id_new)
 Set the slave ID. More...
 
def set_baudrate (self, int baudrate=9600)
 Set RS485 serial baud rate. More...
 
def do_factory_reset (self)
 Restore factory default settings. More...
 

Public Attributes

 master
 
 slave_id
 

Static Public Attributes

int FREQ_REG_OFFSET = 40000
 
int DUTY_REG_OFFSET = 40112
 
int SLAVE_ID_REGISTER = 40254
 
int BAUDRATE_REGISTER = 40255
 
int FACTORY_RESET_REGISTER = 40252
 
int FACTORY_RESET_VALUE = 0
 
int BROADCAST_SLAVE_ID = 0xFF
 
dictionary BAUDRATE_KEYS
 

Detailed Description

Control PWM8A04 3-channel PWM output modules via RS-485 Modbus RTU.

The PWM8A04 seem to come with a pre-set slave ID of 1.

Brand name is "eletechsup", available at https://www.eletechsup.com

This is for the three-channel variant.

Member Function Documentation

◆ do_factory_reset()

def cheap_modbus_rtu.cheap_modbus_io.ModbusModuleABC.do_factory_reset (   self)
inherited

Restore factory default settings.

   You must cycle the power supply after this command.

   Expect a CRC mismatch error when invoking this function,
   I don't know if this is always the case.

Reimplemented in cheap_modbus_rtu.cheap_modbus_io.RelayModule.

◆ get_output_duty()

int cheap_modbus_rtu.cheap_modbus_io.PWM8A04.get_output_duty (   self,
int  output_no 
)

Return the current PWM duty cycle setpoint value for output.

Parameters
output_noOutput number, can be 1, 2 or 3
Returns
PWM duty cycle in percent, valid range is 0...100

◆ get_output_frequency()

int cheap_modbus_rtu.cheap_modbus_io.PWM8A04.get_output_frequency (   self,
int  output_no 
)

Return the current frequency setpoint for output.

Parameters
output_noOutput number, can be 1, 2 or 3
Returns
Frequency of PWM in Hz, valid range is 1...20000

◆ get_slave_id()

int cheap_modbus_rtu.cheap_modbus_io.ModbusModuleABC.get_slave_id (   self)
inherited

Sends a broadcast query to all devices on the bus.

   This only works when only one device is attached to the bus
Returns
The first found slave ID.

◆ set_baudrate()

def cheap_modbus_rtu.cheap_modbus_io.ModbusModuleABC.set_baudrate (   self,
int   baudrate = 9600 
)
inherited

Set RS485 serial baud rate.

   Most devices require cycling the power supply after running this command
   before the new baud rate applies.
Warning
While usually undocumented, it is possible that the device writes directly to FLASH, thus frequent writes could damage the chip!
Parameters
baudrateCan be 1200, 2400, 4800, 9600 (default) or 19200

Reimplemented in cheap_modbus_rtu.cheap_modbus_io.RelayModule.

◆ set_output_duty()

def cheap_modbus_rtu.cheap_modbus_io.PWM8A04.set_output_duty (   self,
int  output_no,
int  duty 
)

Set PWM duty cycle for output (high-active)

Parameters
output_noOutput number, can be 1, 2 or 3
dutyPWM duty cycle in percent, valid range is 0...100

◆ set_output_frequency()

def cheap_modbus_rtu.cheap_modbus_io.PWM8A04.set_output_frequency (   self,
int  output_no,
int  frequency 
)

Set frequency for PWM output.

Parameters
output_noOutput number, can be 1, 2 or 3
frequencyFrequency of PWM in Hz, valid range is 1...20000

◆ set_slave_id()

def cheap_modbus_rtu.cheap_modbus_io.ModbusModuleABC.set_slave_id (   self,
int  slave_id_new 
)
inherited

Set the slave ID.

Warning
While usually undocumented, it is possible that the device writes directly to FLASH, thus frequent writes could damage the chip!
Parameters
slave_id_newNew Modbus slave ID

Reimplemented in cheap_modbus_rtu.cheap_modbus_io.RelayModule.

Member Data Documentation

◆ BAUDRATE_KEYS

dictionary cheap_modbus_rtu.cheap_modbus_io.PWM8A04.BAUDRATE_KEYS
static
Initial value:
= {
1200: 0, 2400: 1, 4800: 2, 9600: 3, 19200: 4, 38400: 5, 57600: 6, 115200: 7
}

The documentation for this class was generated from the following file: