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

这就是地址文档看起来像">

P   12458       Q2  4DW12458 = 1ND20_Q2P(F)
Q   12462       Q2  4DW12462 = 1ND20_Q2Q(F)
S   12466       Q2  4DW12466 = 1ND20_Q2S(F)
I   12470       Q2  4DW12470 = 1ND20_Q2I(F)
U   12474       Q2  4DW12474 = 1ND20_Q2U(F)
f   12478       Q2  4DW12478 = 1ND20_Q2f(F)
EP_POB  12482       Q2  4DW12482 = 1ND20_Q2EP_POB(F)
EP_ODD  12486       Q2  4DW12486 = 1ND20_Q2EP_ODD(F)
EQ_IND  12490       Q2  4DW12490 = 1ND20_Q2EQ_IND(F)
EQ_POJ  12494       Q2  4DW12494 = 1ND20_Q2EQ_POJ(F)
THDVL1  12498       Q2  4DW12498 = 1ND20_Q2THDVL1(F)
THDVL2  12502       Q2  4DW12502 = 1ND20_Q2THDVL2(F)
THDVL3  12506       Q2  4DW12506 = 1ND20_Q2THDVL3(F)
THDIL1  12510       Q2  4DW12510 = 1ND20_Q2THDIL1(F)
THDIL2  12514       Q2  4DW12514 = 1ND20_Q2THDIL2(F)
THDIL3  12518       Q2  4DW12518 = 1ND20_Q2THDIL3(F)
UL1 12522       Q2  4DW12522 = 1ND20_Q2UL1(F)
UL2 12526       Q2  4DW12526 = 1ND20_Q2UL2(F)
UL3 12530       Q2  4DW12530 = 1ND20_Q2UL3(F)
IL1 12534       Q2  4DW12534 = 1ND20_Q2IL1(F)
IL2 12538       Q2  4DW12538 = 1ND20_Q2IL2(F)
IL3 12542       Q2  4DW12542 = 1ND20_Q2IL3(F)
PL1 12546       Q2  4DW12546 = 1ND20_Q2PL1(F)
PL2 12550       Q2  4DW12550 = 1ND20_Q2PL2(F)
PL3 12554       Q2  4DW12554 = 1ND20_Q2PL3(F)
QL1 12558       Q2  4DW12558 = 1ND20_Q2QL1(F)
QL2 12562       Q2  4DW12562 = 1ND20_Q2QL2(F)
QL3 12566       Q2  4DW12566 = 1ND20_Q2QL3(F)
S1  12570       Q2  4DW12570 = 1ND20_Q2S1(F)
S2  12574       Q2  4DW12574 = 1ND20_Q2S2(F)
S3  12578       Q2  4DW12578 = 1ND20_Q2S3(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')

---

[注意]：

你确定想要的float32解码吗？

1. 浮动AB CD==byteorder=Endian.Big, wordorder=Endian.Big
2. 浮动CD AB==byteorder=Endian.Big, wordorder=Endian.Little
3. 浮动BA DC==byteorder=Endian.Little, wordorder=Endian.Big
4. 浮动直流BA==byteorder=Endian.Little, wordorder=Endian.Little

设置unit_id:

• 在许多情况下，unit默认为1

---

[更新]：

也许您需要将结果读取并解码为12482寄存器地址的double/foat64值，因为我认为当文档中的相应寄存器为12482，下一个寄存器为12846时，您需要读取4regs--float64/foat64-double:

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

和

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

Answer 2

我很确定39558853.30的值太大了，无法存储在IEEE单精度浮点中。精度为7.22位，这个数字需要9位。我做了一些实验，将值分配给float，C#中的双值证实了这一点。

这让我相信：

1( 就像Benyamin Jafari建议的那样，你需要读取四个寄存器。然而，十六进制中的数字(作为双精度(是0x4182dcf62a66666，这似乎与您正在读取的任何数据都不对应。

或

2( 它也可能作为UINT32返回，必须按(1/100(缩放才能显示计数器显示的内容。0xE54D4765=3847047013=>按1/100.00=38470470.13缩放，这与您在计数器上看到的内容接近。根据我的经验，这是Modbus中的常见做法。

或

3( 他们正在使用一些其他(非标准(格式来表示数据。

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