Laser LS8000-3 manual Real-Time Data Timing, Transmission Time Fastest Update Rate

LaserSpeed 8000-3 Instruction Handbook

RS-232/RS-422 Communication

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.

Part No. 93463 / Drawing No. 0921-01561 Page 164 of 221 Revision A (Sep 2007)