User manual

Accessory 24E2
Connections 15
Servo Channel Numbering
Each Servo IC has four channels of servo interface circuitry. The tens digit n of the I-variable
configuring the IC represents the channel number on the IC (n = 1 to 4). For example, Channel 1 of the
Standard Servo IC on the first Acc-24E2 is configured by variables I7210 – I7219. These channel-
specific I-variables are represented generically as I7mn0 – I7mn9, where m represents the Servo IC
number (0 – 9) and n represents the IC channel number (1-4).
The Channels 1-4 on the Standard Servo IC of an Acc-24E2 correspond to Channels 1-4, respectively, on
the Acc-24E2 board itself.
I-variables in the I7000s for which the tens digit is 0 (Channel 0) affect all four channels of the PMAC2-
style Servo IC on the Acc-24E2. These multi-channel I-variables are represented generically as I7m00 –
I7m09.
Multi-Channel I-Variables
There are several multi-channel I-variables that must be set up properly for proper operation of the Acc-
24E2 in a Turbo PMAC system. The most important are:
I7m07: Servo IC m Phase/Servo Clock Direction
This variable should be set to 0 the Acc-24E2A generating the clocks (E1 set 2-3) and set to 3 for the
Acc-24C2As to receive the clocks (E1 set 1-2).
I7m00: Servo IC m MaxPhase/PWM Frequency Control
Typically, this will be set to the same value as the variable that controls the system clocks: I7200 on a
UMAC Turbo PMAC2, or I6800 on a Turbo PMAC2 Ultralite. If a different PWM frequency is desired
then the following constraint should be observed in setting this variable:
}Integer{
PhaseFreq
)kHz(PWMFreq*2

I7m01: Servo IC m Phase Clock Frequency Control
Even though the IC is receiving an external phase clock (see I7m07, above), usually it is best to create the
same internal phase clock frequency in the Servo IC. This yields the following constraint:
)17201I(*7200I)101m7I(*00m7I 
{UMAC Turbo}
)16801I(*6800I)101m7I(*00m7I 
{Turbo PMAC2 Ultralite}
Solving for I7m01, we get
1
00m7I
)17201I(*7200I
01m7I 


{UMAC Turbo}
1
00m7I
)16801I(*6800I
01m7I 


{Turbo PMAC2 Ultralite}
If I7m00 is the same as I7200 or I6800, I7m01 will be the same as I7201 or I6801.
I7m02: Servo IC m Servo Clock Frequency Control
Even though the IC is receiving an external servo clock (see I7m07, above), usually it is best to create the
same internal servo clock frequency in the Servo IC. This means that I7m02 for the IC should be set the
same as I7202 on a UMAC Turbo, or the same as I6802 on a Turbo PMAC2 Ultralite.
I7m03: Servo IC m Hardware Clock Frequency Control
The hardware clock frequencies for the Servo IC should be set according to the devices attached to it.
There is no reason that these frequencies have to be the same between ICs. There is seldom a reason to
change this value from the default.