Remote-processing RPC-330 Manual de usuario descargar pdf (Pagina 41)

EXTERNAL INTERRUPT SECTION 12

Page 12-1 RPC-330

DESCRIPTION

Interrupts are useful, and even necessary, when

intermittent signals of short duration require the

processors attention. Signals can be from door switches,

optical interrupters, missing pulse detectors, or other

electronic devices. The ONITR statement directs

program flow to a subrou tine when a n interr upt is

detected.

Two interrupts, IN T 0 and IN T 1, are ava ilable. Both

interrupts are either internally or externally generated.

Internal interrupts are from the quadrature encoder/

counters. This section describes exter nal interrupts.

Both interrupts at connector P2 and P3 are low-going

edge sensitive. Levels are sampled by the CPU every

180 ns, so pulse inputs to any interrupt must be at least

this long. Opto isolated input should have voltage

applied and/ or re moved for at least 10 micro -seconds to

ensure detection. Interrupts may be used to "wake-up"

the card from IDLE mode.

INT 0 and/or IN T 1 may be used as inputs, interrupts,

or both. Refer to SECTION 6, Using Interrupts as

Inputs for accessing using LINE function. When an

INT x line is used as an input or external inter rupt, it

may not be used as a counter interrupt. One interrupt

may be used with a counter and another m ay not, if

desired.

INT 0 is available from one of 3 sources. P2-ISOA and

P2-ISOB are optically isolated. P2-INT 0 is a non-

isolated, TTL input. The third source is from hardware

counter 0. Use jumper header H 2 for INT 0.

INT 1 is a non-isolated, TTL input from P3 or hardware

counter 1. Use jumper header H 3 for INT 1.

Available interrupts are shown in the table below.

H2 and H3 Description

Pins

1-2 Carry pulse from counter

3-4 Borrow pulse from counter

5-6 Exter nal interr upt

7-8 Carry or borr ow pulse from counter

9-10 Latched pulse using quadrature input

ONINT source selection is through jumper H2 and H3.

Pin [5-6] is jumpered to enable external interrupts.

When a counter is used, then its corresponding external

interrupt may not be used. C ounter 0 uses INT 0 and

counter 1 uses INT 1. See SECTI ON 14, Counter Inp uts

for more inform ation.

OPTICALLY ISOLATED

INTERRUPT/INPUT

ISOA and ISOB pr ovide an isolated , high voltage input.

Neither input is connecte d to groun d or + 5V and is

isolated to the card by at least 400 volts.

An exter nal voltage of a t least 3 volts, any polarity, w ill

turn on the isolator. Higher voltages may be used

provided a series resistor is in line to the supply. Use

the following formula to determine the series resistor

needed.

Rs = (Vi - 6) / .005

Where: Vi = input voltage

No series resistor is needed when Rs is negative.

INTERRUPT CHARACTERISTICS

Interrupts are negative going edge sensitive. This means

an interrupt is detected when INT 0 or 1 goes low. INT

0 and 1 must go low for at least 180 ns for reliable

detection. A voltage must be applied to P2-ISOA and

ISOB (INT 0 only) for at least 10 micro-seconds. To

detect a subsequent interrupt, the line must go high or

voltage removed at P2-ISOA or ISOB for at least 10

micro-seconds.

The status of the each interrupt line is read using the

following statement:

100 A = LINE(8) : REM INT 0

110 A = LINE(9) : REM INT 1

When A = 1, the interru pt is high or no voltage is

applied. When A = 0, the interrupt is low. H2 or H3

pins [5-6] must be jumpered to read a status.

The ONIT R statement responds to interrupts on a

priority basis. When INT 0 and INT 1 both go low

simultaneously, INT 1 is processed before INT 0. When

ONT ICK is active, O NITR processing is delayed until

the ONTICK subroutine is completed. ONTICK can

interrupt an ONITR program.

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