am-wd/AMWD.Protocols.Modbus
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Clearified/fixed description of different protocol implementations

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This commit is contained in:
Andreas Müller
2024-07-17 18:00:16 +02:00
parent 6a63dbb739
commit e830e43c36
3 changed files with 18 additions and 11 deletions
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16
AMWD.Protocols.Modbus.Common/Protocols/RtuOverTcpProtocol.cs
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@@ -6,11 +6,13 @@ using AMWD.Protocols.Modbus.Common.Contracts;
namespace AMWD.Protocols.Modbus.Common.Protocols
{
/// <summary>
/// Implementation of the Modbus RTU over TCP protocol.
/// Implementation of the Modbus RTU over Modbus TCP protocol.
/// </summary>
/// <remarks>
/// The Modbus RTU over Modbus TCP is rarely used.
/// It is a non-standard variant of Modbus TCP that includes the Modbus RTU CRC at the end of the message.
/// It is a non-standard variant of Modbus TCP that includes wrapps a Modbus RTU message within a Modbus TCP message.
/// <br/>
/// Definition found on <see href="https://www.fernhillsoftware.com/help/drivers/modbus/modbus-protocol.html">Fernhill Software</see>.
/// </remarks>
public class RtuOverTcpProtocol : IModbusProtocol
{
@@ -475,16 +477,16 @@ namespace AMWD.Protocols.Modbus.Common.Protocols
// Function code
request[7] = (byte)ModbusFunctionCode.WriteSingleRegister;
byte[] addrBytes = register.Address.ToBigEndianBytes();
request[8] = addrBytes[0];
byte[] addrBytes = register.Address.ToBigEndianBytes();
request[8] = addrBytes[0];
request[9] = addrBytes[1];
request[10] = register.HighByte;
request[10] = register.HighByte;
request[11] = register.LowByte;
// CRC
byte[] crc = RtuProtocol.CRC16(request, 6, 6);
request[12] = crc[0];
byte[] crc = RtuProtocol.CRC16(request, 6, 6);
request[12] = crc[0];
request[13] = crc[1];
return request;

9
AMWD.Protocols.Modbus.Common/README.md
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@@ -59,8 +59,8 @@ Here you have the specific default implementations for the Modbus Protocol.
- ASCII
- RTU
- RTU over TCP
- TCP
- [RTU over TCP]
**NOTE:**
The implementations over serial line (RTU and ASCII) have a minimum unit ID of one (1) and maximum unit ID of 247 referring to the specification.
@@ -68,4 +68,9 @@ This validation is _not_ implemented here due to real world experience, that som
---
Published under MIT License (see [**tl;dr**Legal](https://www.tldrlegal.com/license/mit-license))
Published under MIT License (see [**tl;dr**Legal])
[RTU over TCP]: https://www.fernhillsoftware.com/help/drivers/modbus/modbus-protocol.html
[**tl;dr**Legal]: https://www.tldrlegal.com/license/mit-license