Sensoray 425 Manual do Utilizador descarregar pdf (Página 15)

Page 13 Sensoray Model 425 Instruction Manual

Enhanced Relay Channels

Relay channels 0-15 have enhanced functionality

beyond the basic capabilities of channels 16-47. In

addition to basic relay I/O, these enhanced channels

have mechanisms for detecting and capturing

(recording) state transitions. Captured transitions may

be read by the host and may be programmed to request

ISAbus interrupt service.

Selecting the Edge Type

Enhanced channels may be configured to detect either

rising or falling edge transitions. The Edge Select

types for all enhanced relay channels:

Set a bit to detect rising edges on the associated relay

channel, or zero the bit to detect falling edges. Note

that “rising” or “falling” edges are viewed from the

perspective of data polarity on the local data bus.

Arming Capture

A relay channel must be “armed” before it will capture

a detected edge. Any arbitrary block of enhanced relay

channels may be simultaneously armed by writing to

the Capture Arm port:

Set a bit to enable edge detection for the associated

relay channel, or zero the bit to leave the capture enable

unchanged.

Edge Capture Register

Each enhanced channel is associated with a one-bit

Capture register. The Capture register is responsible for

logging the occurance of a detected edge. When a

selected edge occurs while capture is enabled, the

associated Capture register is set. All Capture registers

may be read simultaneously through the Capture port:

Note that before the Capture register can log a detected

edge, channel capture must be armed. After capturing

an edge, the capture register remains set until explicitly

reset by the host.

Clearing Captured Edges

Sometime after a captured edge is detected, it is

necessary to reset the associated capture register. This

is accomplished by writing to the Capture Disarm port:

Set a bit to disable edge detection and reset the capture

to leave the associated arm and capture registers

unchanged. Note that a group of relay channels may be

simultaneously disarmed by setting multiple bits when

writing to this port.

Interrupts

Enhanced relay channels may be individually

programmed to request interrupt service upon capture

of a detected edge. Enable or disable relay channel

interrupts by writing to the Interrupt Enable port:

Set a bit to enable the associated relay interrupt, or zero

the bit to disable the interrupt. Note that clearing the

interrupt enable has no effect on the capture register.

Programming Sequence

In order for a relay to generate an interrupt request, the

channel must be armed, an edge must be captured, and

the interrupt must be enabled.

A typical application, with interrupts, goes like this:

• Edge Type is selected.

• Channel is armed to enable capture.

• Interrupt is enabled.

• An edge is detected by hardware, setting the capture

• ISR disarms channel, thereby clearing capture register and

negating interrupt request.

• Channel is armed to enable next capture.

Relay 0-15 Edge Select register (base + 34, write only)

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0