Alarms Registers - Siemens 6ES5-424 Technical Reference Manual

Counter module.

Chapter 4

Standard

Software

In order for the MM register to be set to the correct value, it

4.4.3 Alarms Registers

would be necessary to use the PA function for counter 1 after

The AM 951 counter chip and therefore the 6ES5 242 module

the using the PA for any of the other counters. For example:

are organized in such a manner that only counters 1 and 2

PA counter 1; the MM register will be set to 3EH

have alarm registers available to them for use. These registers

PA counter 3; the MM register will be set to O O H

are used to provide a comparison value, when the compare

function is enabled in the MM register.

PA counter 1; the MM register will again be set to 3EH

This is a simple example and it could easily be changed to

operate properly, but this is not the point. The idea of the

example is to show that while using the PA function it is

necessary to make sure that once the MM or the INTM is set,

that it is not changed without the user being aware of the

FBI59 in turn provides an alarm register value for each of the

five counters within the data block. Only the values for

counters 1 and 2 are of any use. The values for counters 3,4,

and 5 are irrelevant. The associated data words within the

data block are listed below.

change.

DW16 Alarm register for Counter 1, active

A solution to this problem would be to write the values for

DW23 Alarm register for Counter 2, active

the MM and INTM registers in each of the data words for the

DW30 Alarm register for Counter 3, irrelevant

five counters. This way the user will not have to be concerned

DW37

that the MM register or the INTM register values will be changed

DW44 Alarm register for Counter 5, irrelevant

on each PA function call.

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