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10 Perform „Adjustment on the fly"
Basically, there are two possibilities of "Adjustment on the fly", both of which operate
in the OP mode and independently of the EtherCAT synchronization mode.
The first option is the execution of the Service Data Objects (SDO) 0x6003. The
description of the functionality of this object can be found in the chapter "Object
6003h: Preset value". The adjustment/preset value is transferred once and thus
asynchronously to the measuring system and set by the measuring system
application.
The second possibility, which is described in this section, is the execution of an
adjustment by means of process data. The controller sends an adjustment / preset
value to the measuring system in the cycle of the EtherCAT application and thus
continuously. To do this, object 0x5004, which contains the adjustment / preset
value, must be mapped into the RxPDO data stream. However, this value is only
activated if the bit 0 has the value 1 in the adjustment control byte. The adjustment
control byte 0x5005 must also be mapped into the RxPDO data stream.
If the measuring system has realized the adjustment/preset request, then it sets the bit
0 to the value 1 in the adjustment status byte 0x5006, which is a component of the
process input data. The control has to acknowledge this by setting the Bit 0 in the
adjustment control byte back to the value 0. The measuring system finally
acknowledges this step by resetting bit 0 in the adjustment status byte to the value 0.
After this last handshake step, the entire adjustment/preset process can start again.
By means of bit 4 in control byte 0x5005, the user has two options:
Absolute adjustment
If this bit has the value 0, the adjustment is carried out absolutely and thus as in the
case of the SDO 0x6003. The position to which the measuring system is set
corresponds to the adjustment value after this process.
If the user has selected an adjustment value which is not less than the measuring
length, then the bit 7 in the control status byte 0x5006 is set to the value 1 for the error
indication and the adjustment is not carried out. In this case, the control must reset bit
0 in control byte 0x5005 to 0, set a permissible adjustment value, and set the bit 0 in
control byte 0x5005 to 1 again.
Relative adjustment
If this bit has the value 1, the adjustment is performed relatively. The position to
which the measuring system is set corresponds to a position value, which results as
the sum of the current position value + adjustment value. If the new position value
exceeds the measuring length, it is set accordingly as overflow, based on the current
measuring length.
Printed in the Federal Republic of Germany
06/20/2017
Risk of injury and damage to property by an actual value jump when the
„Adjustment on the fly" is performed!
The „Adjustment on the fly" should only be performed when the measuring
system is at rest, otherwise the resulting actual value jump must be
permitted in the program and application!
TR - ECE - BA - DGB - 0127 - 04
TR-Electronic GmbH 2016, All Rights Reserved
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