Acces I/O products 104-IIRO-8 User Manual

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Acces I/O products 104-IIRO-8 User Manual Manual pdf 13 page image

Manual 104-IIRO-8(E)13Chapter 5: PROGRAMMINGThe board occupies four consecutive addresses in PC I/O space. The base or starting address is selected duringinstallation and will fall on an eight-byte boundary. The read and write functions are as follows (Model E does notuse Base +2):I/O Address Read WriteBase +0Base +1Base +2Base +3N/ARead Isolated InputsEnable IRQRead digital inputsWrite Relay OutputN/ADisable IRQN/AISOLATED DIGITAL INPUTSIsolated digital input states are read as a single byte from the port at Base Address +1. Each of the eight bitswithin the byte corresponds to a particular digital input. A "1" signifies that the input is energized and a "0"signifies that the input is de-energized.Bit Position D7 D6 D5 D4 D3 D2 D1 D0Iso Digital Input IN7 IN6 IN5 IN4 IN3 IN2 IN1 IN0The board response to inputs is rated at 10 uSec. Sometimes it is necessary to slow down that response toaccommodate AC inputs or in noisy environments. Hardware installation of JUMPERS to implement filtering isprovided.The board supports interrupts on change of state of isolated digital inputs. Thus, it is not necessary tocontinuously poll inputs (by reading at base address +1) to detect any state change. To enable this interruptcapability, read at base address +2. To disable interrupts, write at base address +2 or remove the jumper thatselects interrupt level IRQ2 through IRQ7, IRQ10 through IRQ12, IRQ14, or IRQ15. To clear an IRQ, write tobase address +1.DIGITAL INPUTSDigital input states are read as a single byte from the port at Base Address +3. Each of the eight bits within thebyte corresponds to a particular digital input. A "1" signifies that the input is high and a "0" signifies that the inputis low.Bit Position D7 D6 D5 D4 D3 D2 D1 D0Digital Input DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0