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ROC827 Instruction Manual
Issued Mar-06 Power Connections 3-8
General Calculation
Process
To calculate the power the ROC827 requires:
1. Determine the kind and number of communication modules and the
kind and number of expanded backplanes you are implementing.
Enter those values in the Quantity Used column of Table 3-5.
2. Multiply the P
Typical
value by the Quantity Used. Enter the values in
the Sub-Total column of Table 3-5. Perform this calculation for both
the communications module and the LED.
3. Determine the kind and number of I/O modules you are implementing
and complete Tables 3-6 through 3-15 for those modules. For each
applicable I/O module:
a. Calculate the P
Typical
values and enter them in the P
Typical
columns
of each table. Perform this calculation for the I/O modules, LEDs
(if applicable), channels (if applicable), and any other devices.
b. Calculate the Duty Cycle value for each I/O module and each I/O
channel (as applicable). Enter those values in the Duty Cycle
column of Tables 3-6 through 3-15.
c. Multiply the P
Typical
values by the Quantity Used by the Duty
Cycle on each applicable table. Enter those individual sub-totals
in the Sub-Total column on each table and add the sub-totals to
calculate the Total for the table.
4. Transfer the totals from Tables 3-6 through 3-15 to their respective
lines in the Sub-Total column on Table 3-5.
5. Add the Sub-Total values for Tables 3-6 through 3-15. Enter that
value in the Total for All Modules line on Table 3-5.
6. Add the value from the Total for ROC827 Base Unit to the Total for
All Modules. Enter that result in the Total for ROC827 Base Unit and
All Modules line.
7. Transfer the Other Devices total from Table 3-16 to its respective line
in the Sub-Total column on Table 3-5.
8. Add the values from Total for ROC827 Base Unit, Total for All
Modules, and the total for Other Devices. Enter that value in the Total
for ROC827 Base Unit, All Modules, and Other Devices line.
9. Multiply the value in the Total for ROC827 Base Unit, Total for All
Modules, and Other Devices by 0.25. Enter the result in the Power
System Safety Factor (0.25) line.
Note: This value represents a safety factor to the power system to
account for losses and other variables not factored into the power
consumption calculations. This safety factor may vary depending on
external influences. Adjust the factor value up or down accordingly.