Unable to read float value from a PLC address
2
#!/usr/bin/env python
from pymodbus.constants import Endian
from pymodbus.payload import BinaryPayloadDecoder
from pymodbus.payload import BinaryPayloadBuilder
from pymodbus.client.sync import ModbusTcpClient
import struct
import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.INFO)
ip_address = "192.168.1.55"
client = ModbusTcpClient(ip_address)
if client.connect(): # connection is OK
# write float
#builder = BinaryPayloadBuilder(endian=Endian.Little)
#builder.add_32bit_float(77.77)
#payload = builder.build()
#result = client.write_registers(1, payload, skip_encode=True)
# read floats
result = client.read_holding_registers(28, 2)
decoder = BinaryPayloadDecoder.fromRegisters(result.registers,
endian=Endian.Big)
print str(decoder.decode_32bit_float())
client.close()
var1 = str(decoder.decode_32bit_float())
I m using PyModbus library to read float values from a PLC . I m getting right value from str(decoder.decode_32bit_float()) but failed to put it into a variable var1. It shows error (in decode 32 bit float return unpack(string, handle)[0] struct.error: unpack requires a string argument of length 4).
Thanks in advance
python plc pymodbus
edited Nov 15 '18 at 15:12
Cheche
816218
asked Nov 15 '18 at 11:38
R-TR-T
456
add a comment |
2
#!/usr/bin/env python
from pymodbus.constants import Endian
from pymodbus.payload import BinaryPayloadDecoder
from pymodbus.payload import BinaryPayloadBuilder
from pymodbus.client.sync import ModbusTcpClient
import struct
import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.INFO)
ip_address = "192.168.1.55"
client = ModbusTcpClient(ip_address)
if client.connect(): # connection is OK
# write float
#builder = BinaryPayloadBuilder(endian=Endian.Little)
#builder.add_32bit_float(77.77)
#payload = builder.build()
#result = client.write_registers(1, payload, skip_encode=True)
# read floats
result = client.read_holding_registers(28, 2)
decoder = BinaryPayloadDecoder.fromRegisters(result.registers,
endian=Endian.Big)
print str(decoder.decode_32bit_float())
client.close()
var1 = str(decoder.decode_32bit_float())
I m using PyModbus library to read float values from a PLC . I m getting right value from str(decoder.decode_32bit_float()) but failed to put it into a variable var1. It shows error (in decode 32 bit float return unpack(string, handle)[0] struct.error: unpack requires a string argument of length 4).
Thanks in advance
python plc pymodbus
edited Nov 15 '18 at 15:12
Cheche
816218
asked Nov 15 '18 at 11:38
R-TR-T
456
2
ever worked with streams? when you read a stream - f.e. by printing its str(). it is empty afterward because you are past the data in it ... unless more data comes in its empty and can not deliver more. Tryvar1 = decoder.decode_32bit_float()first , thenprint(var1)- dont use str unless you need a string.
– Patrick Artner
Nov 15 '18 at 11:41
Thanks Patrick it worked i really appreciate it Thanks
– R-T
Nov 15 '18 at 11:44
Thought so :) maybe delete it before it gets too many downvotes. Its the same for filestreams etc - once you read from it you are past the data you just read. Or selfanswer
– Patrick Artner
Nov 15 '18 at 11:51
@R-T Check this POST, I hope would help you up
– Benyamin Jafari
Nov 15 '18 at 22:03
add a comment |
2
2
2
1
#!/usr/bin/env python
from pymodbus.constants import Endian
from pymodbus.payload import BinaryPayloadDecoder
from pymodbus.payload import BinaryPayloadBuilder
from pymodbus.client.sync import ModbusTcpClient
import struct
import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.INFO)
ip_address = "192.168.1.55"
client = ModbusTcpClient(ip_address)
if client.connect(): # connection is OK
# write float
#builder = BinaryPayloadBuilder(endian=Endian.Little)
#builder.add_32bit_float(77.77)
#payload = builder.build()
#result = client.write_registers(1, payload, skip_encode=True)
# read floats
result = client.read_holding_registers(28, 2)
decoder = BinaryPayloadDecoder.fromRegisters(result.registers,
endian=Endian.Big)
print str(decoder.decode_32bit_float())
client.close()
var1 = str(decoder.decode_32bit_float())
I m using PyModbus library to read float values from a PLC . I m getting right value from str(decoder.decode_32bit_float()) but failed to put it into a variable var1. It shows error (in decode 32 bit float return unpack(string, handle)[0] struct.error: unpack requires a string argument of length 4).
Thanks in advance
python plc pymodbus
edited Nov 15 '18 at 15:12
Cheche
816218
asked Nov 15 '18 at 11:38
R-TR-T
456
#!/usr/bin/env python
from pymodbus.constants import Endian
from pymodbus.payload import BinaryPayloadDecoder
from pymodbus.payload import BinaryPayloadBuilder
from pymodbus.client.sync import ModbusTcpClient
import struct
import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.INFO)
ip_address = "192.168.1.55"
client = ModbusTcpClient(ip_address)
if client.connect(): # connection is OK
# write float
#builder = BinaryPayloadBuilder(endian=Endian.Little)
#builder.add_32bit_float(77.77)
#payload = builder.build()
#result = client.write_registers(1, payload, skip_encode=True)
# read floats
result = client.read_holding_registers(28, 2)
decoder = BinaryPayloadDecoder.fromRegisters(result.registers,
endian=Endian.Big)
print str(decoder.decode_32bit_float())
client.close()
var1 = str(decoder.decode_32bit_float())
I m using PyModbus library to read float values from a PLC . I m getting right value from str(decoder.decode_32bit_float()) but failed to put it into a variable var1. It shows error (in decode 32 bit float return unpack(string, handle)[0] struct.error: unpack requires a string argument of length 4).
Thanks in advance
python plc pymodbus
python plc pymodbus
edited Nov 15 '18 at 15:12
Cheche
816218
asked Nov 15 '18 at 11:38
R-TR-T
456
edited Nov 15 '18 at 15:12
Cheche
816218
asked Nov 15 '18 at 11:38
R-TR-T
456
edited Nov 15 '18 at 15:12
Cheche
816218
edited Nov 15 '18 at 15:12
Cheche
816218
edited Nov 15 '18 at 15:12
Cheche
816218
816218
asked Nov 15 '18 at 11:38
R-TR-T
456
asked Nov 15 '18 at 11:38
R-TR-T
456
asked Nov 15 '18 at 11:38
R-TR-T
456
456
2
ever worked with streams? when you read a stream - f.e. by printing its str(). it is empty afterward because you are past the data in it ... unless more data comes in its empty and can not deliver more. Tryvar1 = decoder.decode_32bit_float()first , thenprint(var1)- dont use str unless you need a string.
– Patrick Artner
Nov 15 '18 at 11:41
Thanks Patrick it worked i really appreciate it Thanks
– R-T
Nov 15 '18 at 11:44
Thought so :) maybe delete it before it gets too many downvotes. Its the same for filestreams etc - once you read from it you are past the data you just read. Or selfanswer
– Patrick Artner
Nov 15 '18 at 11:51
@R-T Check this POST, I hope would help you up
– Benyamin Jafari
Nov 15 '18 at 22:03
add a comment |
2
ever worked with streams? when you read a stream - f.e. by printing its str(). it is empty afterward because you are past the data in it ... unless more data comes in its empty and can not deliver more. Tryvar1 = decoder.decode_32bit_float()first , thenprint(var1)- dont use str unless you need a string.
– Patrick Artner
Nov 15 '18 at 11:41
Thanks Patrick it worked i really appreciate it Thanks
– R-T
Nov 15 '18 at 11:44
Thought so :) maybe delete it before it gets too many downvotes. Its the same for filestreams etc - once you read from it you are past the data you just read. Or selfanswer
– Patrick Artner
Nov 15 '18 at 11:51
@R-T Check this POST, I hope would help you up
– Benyamin Jafari
Nov 15 '18 at 22:03
2
2
ever worked with streams? when you read a stream - f.e. by printing its str(). it is empty afterward because you are past the data in it ... unless more data comes in its empty and can not deliver more. Try
var1 = decoder.decode_32bit_float() first , then print(var1) - dont use str unless you need a string.– Patrick Artner
Nov 15 '18 at 11:41
ever worked with streams? when you read a stream - f.e. by printing its str(). it is empty afterward because you are past the data in it ... unless more data comes in its empty and can not deliver more. Try
var1 = decoder.decode_32bit_float() first , then print(var1) - dont use str unless you need a string.– Patrick Artner
Nov 15 '18 at 11:41
Thanks Patrick it worked i really appreciate it Thanks
– R-T
Nov 15 '18 at 11:44
Thanks Patrick it worked i really appreciate it Thanks
– R-T
Nov 15 '18 at 11:44
Thought so :) maybe delete it before it gets too many downvotes. Its the same for filestreams etc - once you read from it you are past the data you just read. Or selfanswer
– Patrick Artner
Nov 15 '18 at 11:51
Thought so :) maybe delete it before it gets too many downvotes. Its the same for filestreams etc - once you read from it you are past the data you just read. Or selfanswer
– Patrick Artner
Nov 15 '18 at 11:51
@R-T Check this POST, I hope would help you up
– Benyamin Jafari
Nov 15 '18 at 22:03
@R-T Check this POST, I hope would help you up
– Benyamin Jafari
Nov 15 '18 at 22:03
add a comment |
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2
ever worked with streams? when you read a stream - f.e. by printing its str(). it is empty afterward because you are past the data in it ... unless more data comes in its empty and can not deliver more. Try
var1 = decoder.decode_32bit_float()first , thenprint(var1)- dont use str unless you need a string.– Patrick Artner
Nov 15 '18 at 11:41
Thanks Patrick it worked i really appreciate it Thanks
– R-T
Nov 15 '18 at 11:44
Thought so :) maybe delete it before it gets too many downvotes. Its the same for filestreams etc - once you read from it you are past the data you just read. Or selfanswer
– Patrick Artner
Nov 15 '18 at 11:51
@R-T Check this POST, I hope would help you up
– Benyamin Jafari
Nov 15 '18 at 22:03