Reading a bitstream using digital I/O

Hello everyone,


i decided to generate PWM signals using ounter. and read serial data using NI USB-6341.

My problem is i don't know how can i read serial data using NI USB-6341 (without using NI VISA). see the Program...

Serial data should be like this in Hex (95byte):

5555 5555 5555 5555 5555 8540 0101 0286
1001 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 B0

the whole task is:

reading data stored on the PCB (in Actuator for exhaust valve, Test voltage 14V, 300Hz). When read out is activated data is sent over a serial protocol (identical on PWM-IN and PWMOUT line by grounding the signal). To activate readout the following command has to be applied on PWM-IN pin:


frequency 300 Hz ±5
1. Duty cycle 80 ±5 (10 periods)
2. Duty cycle 50 ±5 (10 periods)
3. Duty cycle 10 ±5 (10 periods)

The supply voltage has to be within the specified range during that time. Operation frequency has to be within valid range for the complete activation sequence, otherwise the sequence has to be restarted. Every duty cycle has to be applied for 10 periods. The order of duty cycles has to be complied. After the last duty cycle the data of 95 Byte will be transmitted.

After transmission of the starting sequence the PWM-IN has to be held high and PWM has to be deactivated. Afterwards the actuator transmits the data serially on the PWM-IN and the PWMOUT line. Preferably to be evaluated is the PWM-In line. Data is transmitted identically. During data transmission no monitoring and control will occur. For data transmission a baud rate of 9600Baud/s ±5% is used. To every byte a start and a stop bit is added, complying with an RS232 8N1 interface. A synchronization of the baud rate is recommended.


thanks a lot for your help in advance

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