eModbus: Invalid CRC (RTU Modbus) - RTU06Example

Describe the bug

When using the RTU06Example with an ESP32-WROOM (NodeMCU) Development Board and Modsim64 as a server. The CRC validation fails when reading registers. It is however able to write to registers without issue.

The connection is made via UART (CP2102) to a Windows host.

Expected behavior

It is expected that CRC validation would succeed in both contexts.

To Reproduce

Install Modsim64 (demo or equivalent) Run Example

Example code

RTU06Example (accessed 29/12/2020) https://github.com/eModbus/eModbus/blob/d0e5329e93290076d271f374ed13c654fbf00ef7/examples/RTU06example/main.cpp

I have also attempted to add CRC to a Modbus Message manually with no difference in the outcome:

        ModbusMessage msg = ModbusMessage(1, READ_HOLD_REGISTER, 10, 1);
        RTUutils::addCRC(msg);
        err = MB.addRequest(msg, Token++);
        if (err != SUCCESS)
        {
            ModbusError e(err);
            Serial.printf("Error creating request: %02X - %s\n", (int)e, (const char *)e);
        }

Additional context

I have tried using alternative serial configurations (SERIAL8E1, SERIAL8N2, etc.) to no success.

Modbus Messages recorded via Modsim64 (over UART):

CRC Counters:

Register written to successfully:

MCU Output:

Response: serverID=1, FC=6, Token=00000457, length=6:
01 06 00 0A 12 34 
Error response: E0 - Timeout
Response: serverID=1, FC=6, Token=00000459, length=6:
01 06 00 0A BE EF 
Error response: E0 - Timeout

EDIT: UPDATED incorrect modscan references to modsim.