Document Number: P-SS-004-09 Rev 5
Old Numbers (AS6007H, A-SS-004-20208)
Revised 11/20/2003
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Page
16
Set the Offset of Analog Input 2 (ANOFF2)
By using the analog offset (ANOFF2), you can shift the range across which the gear ratio is
modified. For example, setting ANOFF2 = 5000 mV, an input of –5V generates the nominal gear
ratio, +10 V generates 1.5
*
GEARI/GEARO, and –10 V produces a ratio of 0.5
*
GEARI/GEARO.
By setting the offset to a negative value, cause the gear ratio to reverse directions (i.e., changes in
the analog input causes motor direction to reverse).
Synchronization (Simple PLL)
The SERVO
STAR
S600 supports synchronization between drives. This function acts like a phase-
locked loop (PLL) that is sampled every 250 microseconds. The function relies on any one of the
digital inputs to indicate the command needs to be adjusted by a fixed amount. If the input is high,
a fixed offset is added to the drive command; if it is low, the offset is not added.
To configure a drive for this synchronization, select the input (1 through 4). Using the terminal
screen, set the input mode for that input to 36 (for example, “IN3MODE = 36”). Place the desired
offset in the input’s trigger variable (for example, IN3TRIG = 208). Once every 250 microseconds,
this input is checked. Each time it is high, the value of the input trigger variable is used to increment
the command position. The scaling for the synchronization input is set so that 2
20
= 1 revolution of
the motor if PRBASE = 20 and 2
16
= 1 revolution if PRBASE = 16.
In general, the value of the trigger is set as:
INxTRIG
=
n
x
250 / 60
Where
n
is the desired maximum offset speed in
rpm
. For example, if you wanted a maximum
offset of 50
rpm
, set INxTRIG = 50
x
(250/60) = 208.
PRBASE
PRBASE must always be either 16 or 20. You can check the value of PRBASE in the terminal
window. Normally, PRBASE is 20. The only exception is if your system needs to keep track of
absolute motor position for more than 2048 revolutions. If the value of PRBASE is 16, electronic
gearing may produce a rough output.
FPGA
FPGA selects different functions upon power up. The default value is FPGA = 0. This variable
must be set to FPGA = 1, the digital encoder input (X5). Use the terminal screen to check and set
FPGA.
