Hardware Manual PCD 1 / PCD 2 Series│Document 26 / 737│Edition EN 15│2008-07-22

Saia-Burgess Controls AG

Interrupt inputs

CPUs and expansion housings

3

3.19 Interrupt inputs

3.19.1 Basics

Because of the input filters and the effect of the cycle time, the digital input modules

are not suitable for immediate reaction to events or for rapid counting processes.

Some CPUs have interrupt inputs for this purpose.

When a positive edge is detected at the interrupt input, an associated XOB is called

(e.g. XOB 20). The code in this XOB defines how the unit should react to the event,

e.g. by incrementing a counter.

The code in XOBs called from interrupt inputs must be kept as brief as possible to al-

low enough time between the interrupts to process the rest of the user program.

i

Many FBoxes are intended for cyclic invocation and so not suitable for use in XOBs,OBs,

or only in a limited way.

Exception: the FBoxes in the Graftec family (standard library) are well suited

3.19.2 PCD1.M120/M130 and PCD1.M125/M135

The two interrupt inputs are located on the motherboard and can be connected via

the 6-pole, plug-in terminal block (terminals 20 to 25). Source operation is always

used.

When a positive edge is detected at input INB1, XOB 20 is called; a positive edge at

input INB2 causes XOB 25 to be called. The reaction time up to the XOB 20/25 call

is a maximum of 1 ms. The code in this XOB defines how the unit should react to

the event, e.g. by incrementing a counter (input frequency max. 1 kHz where pulse/

pause each 50%, total of the two frequencies max. 1 kHz). If the relevant XOB is not

programmed, the ERROR LED is switched on or XOB 0 is called.

4 k 7

10 k

25

24

23

22

21

20

PGND

PGND

INB2

INB1 3.3 nF 4k7

μC

68340

Input signals: (always source operation with PCD1.M12x and PCD1.M13x):

H = 15.. 30 V

L = -30..+5 V or no connected