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RTOS/EK-TM4C123GXL: TM4C123 Launchpad Modbus Issue

Praveen Gonsalves
Expert 1095 points
Part Number: EK-TM4C123GXL

Tool/software: TI-RTOS

Hello, 

I'm developing code for modbus slave using TM4C123 lauchpad. The firmware is completed and is working fine when I interface my modbus slave with master simulator on computer. 

My issue is:

I have a data logger device, which when I interface with my modbus slave, the firmware is getting stuck at the following point:

int32_t
UARTCharGet(uint32_t ui32Base)
{
//
// Check the arguments.
//
ASSERT(_UARTBaseValid(ui32Base));

//
// Wait until a char is available.
//
while(HWREG(ui32Base + UART_O_FR) & UART_FR_RXFE)
{
}

//
// Now get the char.
//
return(HWREG(ui32Base + UART_O_DR));
}

After connecting the data logger, when I do step by step debugging, the code gets stuck in the while loop of the above code

The same firmware is working fine when we interface it with simulators(I have tested it with many simulators).

Kindly tell me what exactly is the issue??

Thank you for your time.

Regards

Praveen

 

  • 0
    Guru 117855 points
    Would it not assist your "helper crüe" if you'd - "List" and "Link" - several such Modbus simulators? (best enables others to duplicate your set-up)
  • 0
    TI__Guru**** 183476 points
    Hi Praveen,
    It means that If there are no characters available, it will wait until character is received before returning. Can you take scope capture and check if the master is sending the data?
  • 0 in reply to Charles Tsai
    Guru 117855 points

    Hi Charles,

    Might it prove true that poster's "simulators" do not actually produce (real) output?     Note - poster (does) report success w/that method.      (such explains my earlier "simulator ID" request...)

  • 0 in reply to cb1_mobile
    TI__Guru**** 183476 points
    Hi cb1,
    I didn't see your reply when I replied. Perhaps the simulator reads from the slave much slower than the MCU. Another question to ask the poster is if he is using the interrupt mode and how he sets up the receive interrupt FIFO level to trigger interrupts.
  • 0 in reply to Charles Tsai
    Guru 117855 points

    Hi Charles,

    Re: "Not seeing earlier post"  - that (was) my sense.      As (several) Modbus simulators are, "Reported to Work" - such "success" most always, "Speeds, Eases & Enhances" our troubleshooting in poster's behalf.

    Identifying those simulators which, "succeeded w/TM4C" should prove useful to (others here) as well.     Firm/I have noted that (some) such Modbus simulators do NOT "Play nicely" w/TM4C.     (nor w/other ARM MCUs...)

    Again - poster's listing & linking of  "Several simulators which succeeded" - would surely  assist HIS CAUSE - and that of others...     (most always the goal should be to, "Assist the Helpers!")