没有与仪器的通信(没有应答)

Question

我对minimalmodbus库有问题。从服务器不响应主请求，我想请求读取。我使用的是Raspberry 3模型B+，与Python3.10.1一起使用的是2.0版本的最小Model库。我正在使用Arduino Mega作为从，我也使用一个迷你适配器，串行转换器，USB到RS485是一个转换模块RS485的Arduino。

import serial
import minimalmodbus

instrument = minimalmodbus.Instrument('COM6',1)
instrument.serial.baudrate = 9600
instrument.serial.timeout = 10
instrument.clear_buffers_before_each_transaction = True
instrument.debug = True
temperature = instrument.read_register(1,1)
print(temperature)

MinimalModbus debug mode. Will write to instrument (expecting 7 bytes back): 01 03 00 01 00 01 D5 CA (8 bytes)
MinimalModbus debug mode. Clearing serial buffers for port COM6
MinimalModbus debug mode. No sleep required before write. Time since previous read: 87898406.00 ms, minimum silent period: 4.01 ms.
MinimalModbus debug mode. Response from instrument:  (0 bytes), roundtrip time:10.0 ms. Timeout for reading: 0 ms.

Answer 1

我在Win10 python3.7.9上也有类似的问题。当我写

import minimalmodbus

instrument = minimalmodbus.Instrument('COM3', 2)
instrument.serial.baudrate = 9600
instrument.clear_buffers_before_each_transaction = True

reg_0 = instrument.read_register(0, 0)
reg_1 = instrument.read_register(1, 0)

print(reg_0)
print(reg_1)

instrument.serial.close()

我有错误信息"minimalmodbus.NoResponseError:没有与仪器的通信(没有回答)“。但是，当我写

import minimalmodbus

instrument = minimalmodbus.Instrument('COM3', 2)
instrument.serial.baudrate = 9600
instrument.clear_buffers_before_each_transaction = True
instrument.debug = True

reg_0 = instrument.read_register(0, 0)
reg_1 = instrument.read_register(1, 0)

print(reg_0)
print(reg_1)

instrument.serial.close()

一切正常。我用Arduino UNO做奴隶。在ModbusPoll中，两个注册人阅读正确

Upd。当我用建筑“试着.除了.”一切正常工作

import minimalmodbus

instrument = minimalmodbus.Instrument('COM3', 2)
instrument.serial.baudrate = 9600
instrument.clear_buffers_before_each_transaction = True

try:
    reg_0 = instrument.read_register(0, 0)
except minimalmodbus.NoResponseError:
    reg_0 = instrument.read_register(0, 0)      
reg_1 = instrument.read_register(1, 0)

print(reg_0)
print(reg_1)

instrument.serial.close()