4.12 - AsynchConfig [U12 Datasheet]
Requires firmware V1.1 or higher. This function writes to the asynch registers and sets the direction of the D lines (input/output) as needed.
Execution time for this function is 60 milliseconds or less (typically 48 milliseconds in Windows).
The actual 1-bit time is about 1.833 plus a “full” delay (µs).
The actual 1/2-bit time is about 1.0 plus a “half” delay (µs). full/half delay = 0.833 + 0.833C + 0.667BC + 0.5ABC (µs)
Table 4.12-1. Common baud rates
Rate | Full A,B,C | Half A,B,C |
1 | 55,153,232 | 114,255,34 |
10 | 63,111,28 | 34,123,23 |
100 | 51,191,2 | 33,97,3 |
300 | 71,23,4 | 84,39,1 |
600 | 183,3,6 | 236,7,1 |
1000 | 33,29,2 | 123,8,1 |
1200 | 23,17,4 | 14,54,1 |
2400 | 21,37,1 | 44,3,3 |
4800 | 10,18,2 | 1,87,1 |
7200 | 134,2,1 | 6,9,2 |
9600 | 200,1,1 | 48,2,1 |
10000 | 63,3,1 | 46,2,1 |
19200 | 96,1,1 | 22,2,1 |
38400 | 3,5,2 | 9,2,1 |
57600 | 3,3,2 | 11,1,1 |
100000 | 3,3,1 | 1,2,1 |
115200 | 9,1,1 | 2,1,1 or 1,1,1 |
When using data rates over 38.4 kbps, the following conditions need to be considered:
When reading the first byte, the start bit is first tested about 11.5 µs after the start of the tx stop bit.
When reading bytes after the first, the start bit is first tested about “full” + 11 us after the previous bit 8 read, which occurs near the middle of bit 8.
When enabled, STB does the following to aid in debugging asynchronous reads:
STB is set about 6 µs after the start of the last tx stop bit, or about “full” + 6 us after the previous bit 8 read.
STB is cleared about 0-2 us after the RX start bit is detected.
STB is set after about “half”.
STB is cleared after about “full”.
Bit 0 is read about 1 µs later.
STB is set about 1 µs after the bit 0 read.
STB is cleared after about “full”.
Bit 1 is read about 1 µs later.
STB is set about 1 µs after the bit 1 read.
STB is cleared after about “full”.
This continues for all 8 data bits and the stop bit, after which STB remains low.
Declaration:
long AsynchConfig ( long *idnum, long demo, long timeoutMult, long configA, long configB, long configTE, long fullA, long fullB, long fullC, long halfA, long halfB, long halfC )
Outputs:
*idnum – Returns the local ID or –1 if no LabJack is found.