Laser beta lasermike LS8000-3 - Manual (Page 164)

LaserSpeed 8000-3 Instruction Handbook
RS-232/RS-422 Communication
Part No. 93463 / Drawing No. 0921-01561 Page 164 of 221 Revision A (Sep 2007)
Real-Time Data Timing
When transmitting data at fast update rates, consideration must be given to the amount
of time that it takes to transmit a single message. If the transmission time exceeds the
update rate, it is impossible for the LS8000-3 to transmit all data. Ethernet UDP is fast
enough that this does not occur, but it can occur over RS-232 and RS-422. For
example, if the RS-232 baud rate were set to 57.6k, a TE data reading would take
4.86ms to transmit. If the User Update Rate is set to 4ms, this will result in every other
message being skipped, resulting in an actual update rate of 8 ms. The gauge's
measurements will not be affected by this—it will still produce accurate measurements.
The following table lists the fastest update rate possible for each baud rate. If using TB
mode, the framing must be set to an 8n1 mode.
Transmission Time Fastest Update Rate
Baud Rate 1 Byte TE TB TE TB
230.4k 43.4µs 1.22ms 694µs 2ms 1ms
115.2k 86.8µs 2.43ms 1.39ms 3ms 2ms
57.6k 173µs 4.86ms 2.78ms 5ms 3ms
38.4k 226µs 7.29ms 4.16ms 8ms 5ms
19.2k 521µs 14.6ms 8.33ms 15ms 9ms
9600 1.04ms 29.2ms 16.7ms 30ms 17ms
4800 2.08ms 58.3ms 33.3ms 59ms 34ms
When sending real-time data over Ethernet, you can either use the UDP or TCP
protocols, but UDP is recommended. The TCP protocol has so much overhead that
the maximum update rate will be on the order of 200ms. The UDP protocol has very
little overhead, so it is easily able to transmit data every 1ms.