ahio.drivers.snap7.Driver Class Reference

Inheritance diagram for ahio.drivers.snap7.Driver:

Public Member Functions
def	__enter__ (self)
def	__exit__ (self, exc_type, exc_value, traceback)
def	setup (self, address, rack=0, slot=1, port=102)
	Connects to a Siemens S7 PLC. More...
def	available_pins (self)
def	analog_references (self)
Public Member Functions inherited from ahio.abstract_driver.AbstractDriver
def	available_pins (self)
	Returns available pins. More...
def	map_pin (self, abstract_pin_id, physical_pin_id)
	Maps a pin number to a physical device pin. More...
def	mapped_pins (self)
	Returns a dictionary containing the mapped pins. More...
def	set_pin_interpolation (self, pin, read_min, read_max, write_min, write_max)
	Interpolates input and output values for pin. More...
def	set_pin_direction (self, pin, direction)
	Sets pin pin to direction. More...
def	pin_direction (self, pin)
	Gets the ahio.Direction this pin was set to. More...
def	set_pin_type (self, pin, ptype)
	Sets pin pin to type. More...
def	pin_type (self, pin)
	Gets the ahio.PortType this pin was set to. More...
def	write (self, pin, value, pwm=False)
	Sets the output to the given value. More...
def	read (self, pin)
	Reads value from pin pin. More...
def	analog_references (self)
	Possible values for analog reference. More...
def	set_analog_reference (self, reference, pin=None)
	Sets the analog reference to reference More...
def	analog_reference (self, pin=None)
	Returns the analog reference. More...
def	set_pwm_frequency (self, frequency, pin=None)
	Sets PWM frequency, if supported by hardware. More...

Detailed Description

Definition at line 38 of file snap7.py.

Member Function Documentation

__enter__()

def ahio.drivers.snap7.Driver.__enter__

(

self

)

Definition at line 41 of file snap7.py.

__exit__()

def ahio.drivers.snap7.Driver.__exit__	(		self,
			exc_type,
			exc_value,
			traceback
	)

Definition at line 44 of file snap7.py.

analog_references()

def ahio.drivers.snap7.Driver.analog_references

(

self

)

Definition at line 138 of file snap7.py.

available_pins()

def ahio.drivers.snap7.Driver.available_pins

(

self

)

Definition at line 93 of file snap7.py.

setup()

def ahio.drivers.snap7.Driver.setup	(		self,
			address,
			rack = 0,
			slot = 1,
			port = 102
	)

Connects to a Siemens S7 PLC.

Connects to a Siemens S7 using the Snap7 library. See the snap7 documentation for supported models and more details.

It's not currently possible to query the device for available pins, so available_pins() returns an empty list. Instead, you should use map_pin() to map to a Merker, Input or Output in the PLC. The internal id you should use is a string following this format: '[DMQI][XBWD][0-9]+.?[0-9]*' where:

• [DMQI]: D for DB, M for Merker, Q for Output, I for Input
• [XBWD]: X for bit, B for byte, W for word, D for dword
• [0-9]+: Address of the resource
• [0-9]*: Bit of the address (type X only, ignored in others)

For example: 'IB100' will read a byte from an input at address 100 and 'MX50.2' will read/write bit 2 of the Merker at address 50. It's not allowed to write to inputs (I), but you can read/write Outpus, DBs and Merkers. If it's disallowed by the PLC, an exception will be thrown by python-snap7 library.

For this library to work, it might be needed to change some settings in the PLC itself. See the snap7 documentation for more information. You also need to put the PLC in RUN mode. Not however that having a Ladder program downloaded, running and modifying variables will probably interfere with inputs and outputs, so put it in RUN mode, but preferably without a downloaded program.

• address IP address of the module.
• rack rack where the module is installed.
• slot slot in the rack where the module is installed.
• port port the PLC is listenning to.

Exceptions

RuntimeError	if something went wrong
any	exception thrown by snap7's methods.

Definition at line 89 of file snap7.py.

---

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

• ahio/drivers/snap7.py