Question

我被分配执行任务而没有任何文档。我从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

我对您的代码进行了如下改进：

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("There isn't the registers, 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')

[注意]：

您确定想要的float32解码吗？

浮动AB CD == byteorder=Endian.Big, wordorder=Endian.Big
浮动CD AB == byteorder=Endian.Big, wordorder=Endian.Little
浮动BA DC == byteorder=Endian.Little, wordorder=Endian.Big
浮动DC BA == byteorder=Endian.Little, wordorder=Endian.Little

设置单位ID ：

在许多情况下，unit是1作为默认ID。

[更新]：

也许您需要在12482寄存器地址读取和解码为 double / float64 值，因为我认为当文档中所需的寄存器为12482时，下一个寄存器是12846，因此我们需要阅读 4regs （ float64 / double ）：

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

和

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

Answer 2

我非常确定39558853.30的值可以存储在IEEE单精度浮点数中。有7.22位精度，该数字需要9位数字。我做了一些实验，将值赋给float和C＃中的double值确认了这一点。

这使我相信：

1）像本雅明·贾法里（Benyamin Jafari）建议的那样，您需要读取四个寄存器。但是，以十六进制表示的数字（双精度）是0x4182dcf62a666666，这似乎与您正在读取的任何数据都不对应。

OR

2）也有可能将它作为UINT32返回，必须将其缩放为（1/100）才能提供计数器显示的内容。 0xE54D4765 = 3847047013 =>按1 / 100.0 = 38470470.13缩放，这与您在柜台上看到的相近。以我的经验，这是Modbus中的常见做法。

OR

3）他们使用其他（非标准）格式来表示数据。

您能给我们产品名称，型号等吗？

Pymodbus读取保持寄存器

2 个答案: