Motoplus DX200. How bis is "Target Buffer" size? mpMotTargetSend().

Hi guys, I'm working on a DX200 project.
I need to know how big is the target buffer by function mpMotTargetSend.
So I write this code.

void func2()
{mpMotStop(0);
    mpMotTargetClear(0x0f, 0);
    int id;
    for (id = 1; id < 21; id++)
    {
        sendProfileAndTargetFromPosVar(grpNo, id, id-1, TIMEOUT_SEND_TARGET_MS);
        setDVar(USER_TARGET_HAS_SENT, id);
        mpTaskDelay(10);
    }
    waitServoOn(100);
    mpMotStart(0);
}

The setDVar write to user D variables, TIMEOUT_SEND_TARGET_MS = 5000ms.
The id increases rapidly to 12, then it increases each 5seconds, so function mpMotTargetSend gets in timeout ERROR.
So, is the target buffer size just 12?
Thank you so much