Siemens SINUMERIK 840C User Manual
Page 202
09.95
6 NC Machine Data (NC MD), NC Setting Data (NC SD)
6.2 General machine data (general data)
Position control basic cycle time
155
Default value
Lower input limit
Upper input limit
Units
4
1
1)
40
Multiple of drive basic
cycle time
Active on
Power On
The sampling interval is defined as the time after which the control outputs a new setpoint
speed to the axes. For axes or spindles, this NC MD can be additionally influenced, i.e. slowed
down by means of a multiplier (NC MD 1396* and 466*).
See Section Axis (Analog) and Spindle Installation.
Table with possible input values
System cycle
ms
(MD 168)
Servo cycle
ms
(MD 155)
IPO cycle
ms
(MD 160)
MD 168
MD 155
MD 160
1
ms
8
ms
32
ms
16
8
4
1
ms
4
ms
16
ms
16 *
4 *
4 *
0.75
ms
3
ms
12
ms
12
4
4
0.625 ms
2.5
ms
10
ms
10
4
4
0.5
ms
2
ms
8
ms
8
4
4
0.5
ms
1
ms
4
ms
8
2
4
0.5
ms
2)
1
ms
2)
3
ms
2)
8
2)
2
2)
3
2)
0.125 ms
3)
as from SW 4
0.125 ms
3)
as from SW 4
1
ms
3)
as from SW 4
2
3)
as from SW 4
1
3)
as from SW 4
8
3)
as from SW 4
OFF delay for servo enable
156
Default value
Lower input limit
Upper input limit
Units
200
0
1 000
ms
Active on
Power On
The enable signal for the speed controller (servo enable) on the measuring circuit is removed
when the programmed delay time has elapsed. There is a separate servo enable signal on the
measuring circuit for each axis; the control supplies these signals on a mode group basis.
The programmed delay time has the following effects:
1.
Once the interpolator has reached the programmed position, the clamping tolerance
(MD 212*) is activated when the delay time has elapsed. The following error must therefore
be smaller than the clamping tolerance at this instant. The delay must be chosen so that it
is possible to reduce to zero the largest possible following error (rapid traverse). In the
event of an error, the servo enable signal is revoked on the measuring circuit and alarm
112* (zero-speed monitoring) activated.
This applies only when NC MD 372* (zero-speed monitoring delay) is 0.
_______
*
Standard value
1)
The lower limits only apply if the control is operated with one channel and 3 axes.
2)
486 CPU only.
3)
486 DX2 or DX4 only.
©
Siemens AG 1992 All Rights Reserved 6FC5197- AA50
6–17
SINUMERIK 840C (IA)