Entering the acquisition parameters for an absolute encoder

(Original Document)

Role

This operation allows you to define an ’s adjustment parameters .

Preliminary conditions

This operation requires that an absolute encoder has already been configured.

Procedure

The following table describes the operations to be performed:

Step	Action
1	In the browser, double-click on Acquisition. Result:
2	Enter the Axis parameters. The parameters that are displayed depend on the reading format chosen in the configuration: Type 1: number of pulses per cycle. Type 2: number of pulses per cycle and number of cycles. Note: Choose a value to the power of 2, for the number of pulses per cycle. Min. value: number of pulses per cycle = 256 and number of cycles = 1 Max. value: 214 (see the formula in step 5 of the table).
3	Enter the encoder offset value (angle and cycle) to obtain a position value equal to 0 when the axis arrives at the machine 0. This value is the gross value provided by the encoder when the axis is on the machine 0. The values consist of: 0 to No of pulses/cycle for the encoder offset on the angle, 0 to No of cycles for the encoder offset on number of cycles.
4	Enter the axis play value. This value is used to compensate for the position error caused by changing the direction of rotation, if there is mechanical play between the drive and the (encoder) axis. forward, declare a negative correction value. The correction will be made on reverse movements, reverse, declare a positive correction value. The correction will be made on forward movements. A value of 0 corresponds to no correction. The values are between -(No of pulses/cycle) /2 and +(No of pulses/cycle) /2. The correction value cannot exceed 1023 pulses. Note: this correction modifies the switching position of all the cams according to the declared value. Whatever the value of the backlash entered, the position and captures values sent to the PLC are current values (no corrections).
5	Enter the reduction factor. This factor reduces the encoder resolution. The position given by the encoder is divided by the reduction factor. This enables the cam program to be effective over a narrower range of pulses than that given by the machine. Possible reduction factor values: 1 (the cam program reacts in relation to the actual position of the encoder, no reduction), 2 (the position given by the encoder is divided by 2, 4, 8, 16 or 32). In addition the following relationship must be checked:
6	Enter the recalibration value (angle and cycle). This recalibration value is systematically added to the position value after correction of the encoder offset. It moves the axis in relation to the machine reference point. The values consist of: 0 to No of pulses/cycles for the recalibration on the angle, 0 to No of cycles for recalibration on the number of cycles. Note: The position value (angle and cycle) after offset correction and recalibration application is: Position value = Gross encoder value - Offset + Recalibration

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.

This type of encoder directly delivers the numeric value of the axis position. The position reading is kept in case of power outage.

These are all the external elements that control the movements of the machine (reducer, encoder…).

The configuration gathers together the data which characterizes the machine (invariant) and which is necessary for the TSX CCY 1128 module to operate.

All this information is stored in the PLC %KW constants zone. The PLC application cannot modify them.

This is the number of pulses delivered by the axis per cycle.

This is the rough value delivered by an absolute encoder to the machine zero.

By completing the adjustment parameter "Offset encoder", it is possible to set the angle value of the axis to 0 on the machine zero position.

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.

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.

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.