Rockwell Automation 1395 Digital Reference Adapter Board - Manual (Page 58)

Chapter 6
StartĆUp
6-12
Digital Reference Adapter Board
Digital Reference Input
Figure 6.7
Lead/Follower Example
DRIVE 1 DRIVE 2 DRIVE 3 DRIVE 4
LEAD FOLLOWER FOLLOWER FOLLOWER
Must have Digital
Reference Adapter
Must have Digital
Reference Adapter
Must have Digital
Reference Adapter
Encoder: 1024
Motor 1: 850/1700 Motor 2: 1750/2000 RPM Drive 2
to follow encoder motor 1 so
that 1750 RPM Drive 2 = 875
RPM Drive 1
Motor 3: 850/1750 RPM Drive 3
to follow encoder motor 1 so
that 875 RPM Drive 3 = 875
RPM Drive 1
Motor 4: 2500 RPM Drive 4 to folĆ
low encoder motor 1 so that 2500
RPM Drive 4 = 1250 RPM Drive 1
Drive # 2 Explanation of Operation:
1. The output of the Digital scaling block will be 4096 when the encoder is
running at the speed specified by parameter 564, in this case 875 RPM.
2. This value is then summed with the Offset Value (param 565), in this
case zero, and passed to the digital multiplier selector.
3. The resulting value is multiplied by one of two multiplier constants as
specified by the digital multiplier selector, parameter 569. In this
example the Digital Multiplier Constant parameter (param 568) is used.
A multiplier constant of 1000 multiplies the value of 1.000 and the final
result becomes 4096.
4. The final value is available by linking to the Digital Reference whole
parameter (param 403) and the Digital Reference Fractional (if required)
parameter (param 404). Since the Digital Reference Whole parameter
(param 403) is linked to the Velocity Reference Whole parameter
(param154) the final value becomes the velocity reference for the Drive.
5. The example is valid when one drive is used.
6. The number of follower drives is limited to three to avoid damage to the
encoder line driver.