Time Setting (System) - Fagor CNC 8060 Installation Manual

I n s t a l l a t i o n m a n u a l .
2.3.7

Time setting (system).

LOOPTIME
CNC cycle (loop) time.
Possible values: From 0 to 20 ms.
Default value: 4 ms.
Associated variable: (V.)MPG.LOOPTIME
This parameter sets the CNC's loop time. Loop time greatly depends on the number of inputs,
outputs and analog axes of the bus. The shorter the loop time, the less time will the CPU
have to process the data.
Influence of the analog axes on parameter LOOPTIME.
Use the following orientative values:
LOOPTIME
4 ms.
5 ms.
6 ms.
8 ms.
10 ms.
Influence of the CAN bus on parameter LOOPTIME.
From the CAN bus point of view, the minimum loop time for a particular configuration mainly
depends on the traffic requirements of the system; in other words, by the time consumed
by the transmission of messages per cycle. The factors affect it are the following:
• Total number of remote feedbacks enabled.
• Total number of analog inputs, analog outputs and keyboard handwheels.
• Total number and changing frequency of digital inputs and outputs.
• Frequency of the PLC's PRG module (PRGFREQ).
• CAN transmission speed.
For an exact measurement of the minimum loop time required for a particular configuration,
the most reliable thing to do is to use an off-the-shelf tool for a logic analysis of the CAN bus.
This tool may be used to set parameter LOOPTIME with a value that covers the
communicating requirements reliably, but without saturating the bandwidth of the system (we
recommend not to take more than 60% of the bus) to prevent possible transient peaks of
traffic or asynchronous eventualities.
If the value of parameter LOOPTIME is too low, the bus will behave as follows.
CANfagor
CANopen
In either case, it would be necessary to increase the value of parameter LOOPTIME or
decrease the communication time of the system (increasing the CAN speed, increasing the
value of parameter PRGFREQ or removing physical elements).
Number of analog axes.
Up to 8 analog axes.
Up to 12 analog axes.
Up to 16 analog axes.
Up to 20 analog axes.
Up to 24 analog axes.
If the CNC's loop time is too short to manage the desired configuration, it will
issue several errors indicating cycle overlapping and timeout in cyclic CAN
readings.
On CNC startup, it runs an estimate of the amount of time required and it will
issue a warning if it is too short.
2.
CNC 8060
CNC 8065
(R : 1709)
EF
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