Parameter RS232 use for win real-time target

Hello everybody,

i'm trying to read out a sensirion fluid flow sensor. its connected via rs-232 serial port (com1). The Aim is to read the sensor out in "real-time"- the max-frequency is 200 Hz. so i've got three question:

1. am i right if the baudrate is 19200 and the information is given in 8 bits plus 1 stop bit and i need 6 bytes so the system has to transmit 54bits in these 5ms? (and 19200*0.005=96 are max?)

2.it worked without delay only once...now i have normaly a delay of ~6s, witch is the whole standard-buffer (512bytes filled in 6s- 200Hz,4Bytes per measurement, so i thought it must be kind of a FIFO-system. but tthe buffer was reduced to just the 6 bytes i need to work with all the time

3. are the paramters for real-time target -blocks. i cant get the normal serial-blocks running in the real-time target. i tryed to use the real-time-blocks but couldnt find the right parameters. (Baud Rate 19200 Data Bits 8 Stop Bits 1 Parity none Protocol none Echo the sensor generates an echo)

i would be very lucky if somebody could help me! thanks

greetings Hansjörg

Answer 1

[Walter Roberson]

You missed the 1 start bit. With 1 stop bit and 1 start bit and 8 bits per byte, a total of 10 bits per byte is sent, which would be 60 bits for 6 bytes. That would be 1920 bytes per second at most, which would have time for up to 320 Hz.

With regard to the delay in reading: be sure to turn the terminator character off so that the read routines do not wait for a timeout when they do not get the terminator.

[Hansjörg]

thanks...your're right!

so the pace of the system should be no problem.

is there another posibility to limit the buffer (obj.inputbuffersize = **)or do i just reduce the output of the buffer and the buffer is the same size and i get just the last **bytes out?

i think the terminator was off...but i'll check this.