bug(Modbus): 使用IModbusTcpClient.WriteMultipleRegistersAsync发送1个寄存器时生成的数据不正确

[water1983]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

使用modbusTcp.WriteMultipleRegistersAsync(1, 0, new ushort[] { 6 });发送只有一个寄存器的内容时，生成的字节数据不正确，PLC返回错误3(错误的数据)。

见图片，红色箭头和上面的蓝色箭头是相同的数据，BB生成的和调试助手生成的不同
对比调试助手生成的内容，应该是BB使用了FC16功能码但数据包的格式却是FC6的。

如果发送多个寄存器modbusTcp.WriteMultipleRegistersAsync(1, 0, new ushort[] { 6, 8 });
则正常
见图片，绿色箭头和下面的蓝色箭头是相同的数据，BB生成的和调试助手生成相同

我查看了modbus的源码
https://github.com/LongbowEnterprise/Longbow.Utility2026/blob/main/src/Longbow.Modbus/Utility/MessageBuilder.cs#L68
这里拼接数据时似乎没有考虑FC06
https://github.com/LongbowEnterprise/Longbow.Utility2026/blob/main/src/Longbow.Modbus/Interfaces/ModbusClientBase.cs#L45
和FC16
https://github.com/LongbowEnterprise/Longbow.Utility2026/blob/main/src/Longbow.Modbus/Interfaces/ModbusClientBase.cs#L58
功能码数据结构不同的问题
当调用FC16(WriteMultipleRegistersAsync)但数据只有1个寄存器时，却按照FC06的格式拼接的数据

Expected Behavior

modbusTcp.WriteMultipleRegistersAsync能够正常发送只有1个寄存器内容的数据

Interactive render mode

Interactive Server (Interactive server-side rendering (interactive SSR) using Blazor Server)

Steps To Reproduce

压缩包为啥上传不了，请看一下描述，如果需要工程请回复。

核心代码很简单

private void SendFC16()
    {
        var modbusTcp = ModbusFactory.GetOrCreateTcpMaster();

        modbusTcp.ConnectAsync("192.168.1.97", 502);
        modbusTcp.WriteMultipleRegistersAsync(1, 0, new ushort[] { 6 });
    }

private void SendFC16two()
    {
        var modbusTcp = ModbusFactory.GetOrCreateTcpMaster();

        modbusTcp.ConnectAsync("192.168.1.97", 502);
        modbusTcp.WriteMultipleRegistersAsync(1, 0, new ushort[] { 6, 8 });
    }

Exceptions (if any)

No response

.NET Version

NET10.0

Anything else?

No response

[bb-auto]

@water1983 Thank you for filing this issue. In order for us to investigate this issue, please provide a minimalistic repro project that illustrates the problem.

[water1983]

BootstrapBlazorAppTestModbus.zip

最小项目传上来了

[ArgoZhang]

@water1983 感谢感谢

[ArgoZhang]

@water1983 已修复发布新包 10.0.4