Interface with the PLC program

(Original Document)

General

Although it is independent, the processing of the electronic module is controlled by the sequential program of the PLC processor.

The electronic cam module benefits from:

performances due to the independent module process (independence in relation to the cycles of PLC tasks)
automatic cyclic exchanges with the main program in order to communicate with the other parts of the application.

States are read and commands written via the PLC sequential program using language objects associated with the module: %I, %Q, %M, etc accessible via mnemonics.

Illustration of exchanges

The following diagram illustrates the various exchanges between the electronic cam module and the PLC processor.

Description of the data exchanged

The following table describes the main data that is exchanged.

Type of data	Description
Recipe	The recipe groups together the data required for the module to control the machine for a series of parts. The recipe can be modified or completely changed by the PLC application. All this information is contained in the %MW PLC words in the memory zone reserved for the module. It contains the: data for acquisition: the value of recalibration, play, parameters of the encoder (offset, reduction factor) etc. descriptors of the tracks: parts counter,anticipation… cam descriptors: cam type, threshold values…
Statuses	This data is used to control the electronic cam application in order to supervise, diagnose, or perform operations on the other elements of the application. It contains the values: of the states of the physical inputs of the position reading (angle and number of turns) of the parts counter of the registers of capture of the states of the tracks and the outputs of any faults
Commands	This data is used to control the electronic cam application from the PLC processor program to perform operations on the operating modes, enable the functions, force the outputs, etc. It contains the commands: for starting or stopping the cam program enabling the functions: recalibration, capture, position counting direct commands on the following functions: recalibration, capture, parts counting enabling cams and tracks forcing outputs masking events
Event	Activates the PLC processor event task. The module transmits data to the PLC processor regarding: the source of the event the angle values and number of turns which have been captured

Logic state which switches to 1 when an angular value in the cycle is overshot and which resets to 0 according to the type of cam.

A cam is systematically associated to one and only one track. Several cams can be associated to one track.

Area in which the action of the outputs can be programmed.

The recipe groups together the data required for the module to control the machine for a series of parts. The recipe can be modified or completely changed by the PLC application. All this information is contained in the PLC %MW words in the memory zone reserved for the module.

Module functions that are used to calculate the position reading of the machine.

This is the module function which is used to adjust the axis in relation to the machine zero or to synchronize the axis in relation to the arrival of a part.

Recalibration forces the position reading to a value which is predefined by the "recalibration value" parameter (included in the pulse field of the cycle).

The module allows recalibration to be carried out systematically for each cycle or for only one cycle. This recalibration is always conditioned to the IREC input.

Position sensor accepted by the module It can be incremental, SSI absolute or parallel (via Telefast ABE 7CPA11).

This is the logic state which can be applied to the physical output. The maximum number of tracks is 32.

Cam processor function that is used to compensate for the delay caused by the machine’s actuators.

The anticipation value is applied to all changes of track status. It is specified by the "anticipation factor" defined in the recipe parameters (value between 0 and 32 767 x 50 micro seconds).

Essential feature of a cam. Defines the type of cam calculation according to the angle value (position, monostable or brake command).

A module function that is used to sample the position value of the axis on detection of a precise event (input Icapt0 and/or Icapt1). The capture has no impact on the values of the axis nor on the cam processor.

The implementation of this function allows the application to manage the process better, for example: in monitoring the number of pulses sent by the encoder, the size of the parts, the axis slip, the angle of arrival of the parts.

This is all the internal data that defines the activation of the outputs according to the position reading of the axis. The cam program represents the most important part of the recipe.