JVL MAC050 - Page 87

JVL A/S - User Manual - Integrated Servo Motors MAC050 - 4500 83
2.18 High resolution velocity
High resolution:
Note: Only MAC800-1200 in some versions are available with 8000 CPR encoder.
All other motors are with 8192 CPR encoders.
2.18.3 How to enable high resolution velocity
The general, simple way of using this option is to set bit-26 (value 0x4000000) in register
236, SETUP_BITS, and then Save in Motor.
After a following reset, the target velocity and acceleration registers then work with 64x
higher resolution compared to the default resolution.
For example, to set a velocity of 3000 RPM using a sample time of 1.0 ms and an encoder
resolution of 8000 PPR, set register 5, V_SOLL, to 3000/0.007324218 = 409600 counts.
It is strongly recommended to keep the bit either set or cleared during entire operation
in the application.
If the bit changes when the motor is in an active mode, this will result in corrupted posi-
tions. However, it is possible to change the bit without saving to flash or performing a
reset. This should ONLY be done when the motor is in Passive mode.
One of the consequences of using high-resolution velocity, acceleration is that the inter-
nal position register 8, P_FNC, gets to be a 64-bit value, and will occupy both register
numbers 8 and 9. The INDEX_OFFSET register traditionally in register 9 is then moved
to register 277. It is recommended to avoid writing directly to P_FNC when in high-res
-
olution mode, but instead set it indirectly through FastMac commands and Control Bits
that calculate it from other register, like Register 4, P_NEW.
P_FNC is primarily used in relative movements.
Please be aware of marginal rounding differences between classic mode and high-reso-
lution modes. This can mean some applications must be fine-tuned to reach the same
maximum velocity and acceleration.
Sample
time
Sample
frequency
Encoder resolution
(RPM/count)
Encoder used
8000 CPR
Encoder used
8192 CPR
1.0 ms 1000 Hz 0.007324218 0.007152557
1.3 ms 769.23 Hz 0.005634014 0.005501967
2.0 ms 500 Hz 0.003662109 0.003576278
2.6 ms 384.61 Hz 0.002817007 0.002750983
TT1601-01GB
31 30 29 28 27 26 25 24 23 22
Bit 26: Enable/disable high resolution velocity
Value
0 (default)
1
Function / Influence
High resolution velocity disabled - normal motor function
High resoliution velocity enabled
Register 236 - SETUP_BITS
2120191817161514131211109876543210
Bit 31 - 27 and Bit 25 - 0: Is used for other purposes - do not overwrite these bits