Entering The Monitoring Threshold Values - Siemens SINUMERIK 840C Installation Instructions Manual

12 Functional Descriptions
12.18.13 Start-up
While the following axis is traversing, the positional difference for synchronism (contour
deviation FD) should be approximately 0, otherwise the time constant needs to be re-
optimized.
• Re-optimizing the time constant of the parallel model:
– Change machine data "Time constant parallel model" manually until the positional
difference for synchronism (see above) has been minimized.

Entering the monitoring threshold values

After optimizing the controllers and setting the feedforward control, you must input the
monitoring threshold values.
Calculate the values for synchronism, emergency retraction, etc. depending on the requisite
degree of accuracy and the safety requirements laid down by the machine manufacturer.
These values can be checked via the PLC interface.
The actual position deviation between the following axes and the leading axes is shown in the
service display of the following axes under synchronism error. The emergency retraction can
also be interrogated as a rapid signal on the mixed I/O module.
• Machine data
– NC MD 1436* or 490*
– NC MD 1440* or 491*
– NC MD 1444* or 492*
Measurements are taken in the following drive resolution.
If the two synchronism limits are not reached, then the associated PLC interface signals are
set to "1".
When the emergency retraction threshold is exceeded, a rapid HW signal is released on the
servo level provided the interface signal has enabled the monitoring function. The hardware
signal must be parameterized in NC MD 588*/528*.
The following drive is limited to maximum acceleration and maximum velocity.
In addition, a warning threshold is monitored in both cases, the value of which is defined as a
percentage of the maximum value in NC MD 1448* or 494*. This percentage values applies to
1)
both limits.
If, for example, 50 is entered in MD 276* as the acceleration value, then the NS ACCELERA-
TION WARNING THRESHOLD signal is set when 45 is exceeded in the standard setting,
When faults in the leading drives occur, the following drive switches to controlled follow-up
mode, i.e. traversal with actual values as reference. On expiry of the delay time specified
above, the following drive switches from controlled follow-up to normal follow-up mode.
_______
1) Please note "Parameter set switchover" function description with SW 4 and higher.
12–164
1)
Synchronism fine
1)
Synchronism coarse
Emergency retraction threshold
© Siemens AG 1992 All Rights Reserved
1)
1)
6FC5197- AA50
SINUMERIK 840C (IA)
10.94