RTLinux device driver for Computer Boards CIO-PDISO16 digital I/O board

1. The board

The CIO- PDISO16 is a digital I/O board that has 2*8 relay channels and 2*8 digital inputs. It is designed for control and sensing applications where a few points of high voltage need to be sensed or controlled. The 16 outputs are electromechanical relays. The contacts are rated at 6A @ 120V A. C. or 28V D. C., resistive load. The relays are controlled by writing to two 8 -bit ports. The state of the relays may be determined by a read from the control port address. There are 16 individual, optically isolated (500V) inputs that may be read back as two 8- bit bytes. The inputs are not polarity sensitive and may be driven by either A. C. (50 - 1000 Hz) or D. C. in the range 5V - 24V. Programming is accomplished by writes and reads to the 8- bit ports. Each bit indicates the state of an input or controls an output.

2. Documents

• http://www.computerboards.com
• My device driver user manual: Online reading

3. Software

• device driver source files tar ball
• device driver source file (.c)
• device driver header file (.h)
• common header file (.h) (shared beteen driver and application code)
• access from Linux user space (fifo communication)
• access from RTLinux module (use of the posixio API)
• Makefile (add rtl.mk)
• simply write to port

It is definitely not clean real-time programming ! The driver and the rt_module are polling their fifo to see if a message has been sent. It is just to prove that handlers are only suitable when the communication is established between RTLinux and Linux...

• device driver source file (.c) (polling its fifo, use with dio_fifo module)
• access from RTLinux module (use fifo's) (polling)