python - Pymodbus 读取保持寄存器

Question

我被指派在没有任何文档的情况下执行该任务。我在从 MODBUS 读取数据时遇到问题。这是我能够创建的脚本:

from pymodbus.constants import Endian
from pymodbus.payload import BinaryPayloadDecoder
from pymodbus.payload import BinaryPayloadBuilder
from pymodbus.client.sync import ModbusTcpClient

client = ModbusTcpClient('X.X.X.X')
connection = client.connect()

request = client.read_holding_registers(12606,2)
result = request.registers
decoder = BinaryPayloadDecoder.fromRegisters(result, Endian.Big, wordorder=Endian.Little)
print "Counter1: %0.2f" % decoder.decode_32bit_float()

request = client.read_holding_registers(12482,2)
result = request.registers
decoder = BinaryPayloadDecoder.fromRegisters(result, Endian.Big, wordorder=Endian.Little)
print "Counter2: %0.2f" % decoder.decode_32bit_float()

client.close()

一切看起来都很好，但是计数器上的数据与脚本中的数据不同，例如:

Value on the counter : 39558853.30 (value is decimal)
Value from the script: 58853.30
(value is decimal)

Read input registers (HEX): E54D 4765

这就是地址文档的样子”

P   12458       Q2  4\DW12458 = 1\ND20_Q2\P(F)
Q   12462       Q2  4\DW12462 = 1\ND20_Q2\Q(F)
S   12466       Q2  4\DW12466 = 1\ND20_Q2\S(F)
I   12470       Q2  4\DW12470 = 1\ND20_Q2\I(F)
U   12474       Q2  4\DW12474 = 1\ND20_Q2\U(F)
f   12478       Q2  4\DW12478 = 1\ND20_Q2\f(F)
EP_POB  12482       Q2  4\DW12482 = 1\ND20_Q2\EP_POB(F)
EP_ODD  12486       Q2  4\DW12486 = 1\ND20_Q2\EP_ODD(F)
EQ_IND  12490       Q2  4\DW12490 = 1\ND20_Q2\EQ_IND(F)
EQ_POJ  12494       Q2  4\DW12494 = 1\ND20_Q2\EQ_POJ(F)
THDVL1  12498       Q2  4\DW12498 = 1\ND20_Q2\THDVL1(F)
THDVL2  12502       Q2  4\DW12502 = 1\ND20_Q2\THDVL2(F)
THDVL3  12506       Q2  4\DW12506 = 1\ND20_Q2\THDVL3(F)
THDIL1  12510       Q2  4\DW12510 = 1\ND20_Q2\THDIL1(F)
THDIL2  12514       Q2  4\DW12514 = 1\ND20_Q2\THDIL2(F)
THDIL3  12518       Q2  4\DW12518 = 1\ND20_Q2\THDIL3(F)
UL1 12522       Q2  4\DW12522 = 1\ND20_Q2\UL1(F)
UL2 12526       Q2  4\DW12526 = 1\ND20_Q2\UL2(F)
UL3 12530       Q2  4\DW12530 = 1\ND20_Q2\UL3(F)
IL1 12534       Q2  4\DW12534 = 1\ND20_Q2\IL1(F)
IL2 12538       Q2  4\DW12538 = 1\ND20_Q2\IL2(F)
IL3 12542       Q2  4\DW12542 = 1\ND20_Q2\IL3(F)
PL1 12546       Q2  4\DW12546 = 1\ND20_Q2\PL1(F)
PL2 12550       Q2  4\DW12550 = 1\ND20_Q2\PL2(F)
PL3 12554       Q2  4\DW12554 = 1\ND20_Q2\PL3(F)
QL1 12558       Q2  4\DW12558 = 1\ND20_Q2\QL1(F)
QL2 12562       Q2  4\DW12562 = 1\ND20_Q2\QL2(F)
QL3 12566       Q2  4\DW12566 = 1\ND20_Q2\QL3(F)
S1  12570       Q2  4\DW12570 = 1\ND20_Q2\S1(F)
S2  12574       Q2  4\DW12574 = 1\ND20_Q2\S2(F)
S3  12578       Q2  4\DW12578 = 1\ND20_Q2\S3(F)

Answer 1

我改进了您的代码如下:

from pymodbus.constants import Endian
from pymodbus.payload import BinaryPayloadDecoder
from pymodbus.client.sync import ModbusTcpClient

def validator(instance):
    if not instance.isError():
        '''.isError() implemented in pymodbus 1.4.0 and above.'''
        decoder = BinaryPayloadDecoder.fromRegisters(
            instance.registers,
            byteorder=Endian.Big, wordorder=Endian.Little
        )   
        return float('{0:.2f}'.format(decoder.decode_32bit_float()))

    else:
        # Error handling.
        print("The register does not exist, Try again.")
        return None


client = ModbusTcpClient('X.X.X.X', port=502)  # Specify the port.
connection = client.connect()

if connection:
    request = client.read_holding_registers(12606, 2, unit=1)  # Specify the unit.
    data = validator(request)
    print(data)

    request = client.read_holding_registers(12482, 2, unit=1)  # Specify the unit.
    data = validator(request)
    print(data)

    client.close()

else:
    print('Connection lost, Try again')

<小时/>

[注意]:

您确定所需的 float32 解码吗？

1. 浮点 AB CD == byteorder=Endian.Big, wordorder=Endian.Big
2. float CD AB == byteorder=Endian.Big, wordorder=Endian.Little
3. float BA DC == byteorder=Endian.Little, wordorder=Endian.Big
4. 浮点 DC BA == byteorder=Endian.Little, wordorder=Endian.Little

设置unit_id:

• 在许多情况下，unit 默认为 1。

<小时/>

[更新]:

也许您需要将结果读取并解码为 12482 寄存器地址的 double/float64 值，因为我认为当文档中的相应寄存器为 12482，下一个寄存器是12846，您需要读取4regs - float64/double:

request = client.read_holding_registers(12482, 4, unit=1)

还有

return float('{0:.2f}'.format(decoder.decode_64bit_float()))