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ruby - ModBus TCP communication using Ruby: failing to implement HelloWorld

问题描述

I am able to communicate with a ventilation installation (Helios KWL EC 500 W which supports holding registers only, english description starts at 50% of the file) using the modpoll utility v3.4. But I failed to transfer the very first communication to Ruby and the rmodbus library v1.3.3.

With modpoll, I may request some temperature value with the command

./modpoll -m tcp -a 180 <ipaddr> 0x7630 0x3031 0x3034 0x0000

and then read the data using

./modpoll -m tcp -a 180 -t4:hex -c 8 -0 -1 <ipaddr>
 Protocol configuration: MODBUS/TCP
 Slave configuration...: address = 180, start reference = 1 (PDU), count = 8
 Communication.........: x.x.x.x, port 502, t/o 2.00 s, poll rate 1000 ms
 Data type.............: 16-bit register (hex), output (holding) register table
 -- Polling slave...
 [1]: 0x7630

which outputs 8 16bit registers as stated as example in the Helios modbus documentation. As very first step, I tried to move the read part to Ruby. However, my Ruby code times out:

require 'rmodbus'
ModBus::TCPClient.new(ipaddr, 502) do |client|
  client.with_slave(1) do |slave|
    slave.debug = true
    puts slave.holding_registers[180..187]
  end
end

and throws the exception

/var/lib/gems/2.3.0/gems/rmodbus-1.3.3/lib/rmodbus/slave.rb:241:in `rescue in query': 
Timed out during read attempt (ModBus::Errors::ModBusTimeout)
from /var/lib/gems/2.3.0/gems/rmodbus-1.3.3/lib/rmodbus/slave.rb:232:in `query'
from /var/lib/gems/2.3.0/gems/rmodbus-1.3.3/lib/rmodbus/slave.rb:164:in `read_holding_registers'

What's wrong?

I am not sure if / how to use the parameters output by modpoll "address =180" and "start reference =1". Is "address" equivalent to "holding register #"?

标签： rubymodbus-tcp

解决方案

好吧，这个有点傻。对于记录（以及其他可能想使用 rmodbus 与他们的 Helios 交谈的人）：

slave.debug = 1

打开输出发送到 modbus slave 的字节流的调试。第一个字节序列应该是：事务号（2 个字节），协议说明符（2 个字节，始终为零），以下消息的大小（2 个字节），单元标识符（1 个字节，对于 Helios KWL 始终为 180）。

从站需要使用其单元标识符 180 进行初始化，而不是 1：

client.with_slave(180) do |slave|

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