1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
|
"""
Pymodbus Server With Updating Thread
--------------------------------------------------------------------------
This is an example of having a background thread updating the
context in an SQLite4 database while the server is operating.
This scrit generates a random address range (within 0 - 65000) and a random
value and stores it in a database. It then reads the same address to verify
that the process works as expected
This can also be done with a python thread::
from threading import Thread
thread = Thread(target=updating_writer, args=(context,))
thread.start()
"""
# --------------------------------------------------------------------------- #
# import the modbus libraries we need
# --------------------------------------------------------------------------- #
from pymodbus.server.asynchronous import StartTcpServer
from pymodbus.device import ModbusDeviceIdentification
from pymodbus.datastore import ModbusSequentialDataBlock
from pymodbus.datastore import ModbusServerContext
from pymodbus.datastore.database import SqlSlaveContext
from pymodbus.transaction import ModbusRtuFramer, ModbusAsciiFramer
import random
# --------------------------------------------------------------------------- #
# import the twisted libraries we need
# --------------------------------------------------------------------------- #
from twisted.internet.task import LoopingCall
# --------------------------------------------------------------------------- #
# configure the service logging
# --------------------------------------------------------------------------- #
import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.DEBUG)
# --------------------------------------------------------------------------- #
# define your callback process
# --------------------------------------------------------------------------- #
def updating_writer(a):
""" A worker process that runs every so often and
updates live values of the context which resides in an SQLite3 database.
It should be noted that there is a race condition for the update.
:param arguments: The input arguments to the call
"""
log.debug("Updating the database context")
context = a[0]
readfunction = 0x03 # read holding registers
writefunction = 0x10
slave_id = 0x01 # slave address
count = 50
# import pdb; pdb.set_trace()
rand_value = random.randint(0, 9999)
rand_addr = random.randint(0, 65000)
log.debug("Writing to datastore: {}, {}".format(rand_addr, rand_value))
# import pdb; pdb.set_trace()
context[slave_id].setValues(writefunction, rand_addr, [rand_value])
values = context[slave_id].getValues(readfunction, rand_addr, count)
log.debug("Values from datastore: " + str(values))
def run_dbstore_update_server():
# ----------------------------------------------------------------------- #
# initialize your data store
# ----------------------------------------------------------------------- #
block = ModbusSequentialDataBlock(0x00, [0] * 0xff)
store = SqlSlaveContext(block)
context = ModbusServerContext(slaves={1: store}, single=False)
# ----------------------------------------------------------------------- #
# initialize the server information
# ----------------------------------------------------------------------- #
identity = ModbusDeviceIdentification()
identity.VendorName = 'pymodbus'
identity.ProductCode = 'PM'
identity.VendorUrl = 'http://github.com/bashwork/pymodbus/'
identity.ProductName = 'pymodbus Server'
identity.ModelName = 'pymodbus Server'
identity.MajorMinorRevision = '1.0'
# ----------------------------------------------------------------------- #
# run the server you want
# ----------------------------------------------------------------------- #
time = 5 # 5 seconds delay
loop = LoopingCall(f=updating_writer, a=(context,))
loop.start(time, now=False) # initially delay by time
StartTcpServer(context, identity=identity, address=("", 5020))
if __name__ == "__main__":
run_dbstore_update_server()
|
