When power is turned off under normal conditions, each serial pulse coder's present reading is maintained in the pulse coder by backup batteries on the robot.

• A. False
• B. Only during maintenance
• C. Only when backup batteries are present
• D. True

Answer: (D)

The test is about keeping encoder counts alive when power is removed. The pulse coder uses backup batteries to supply enough energy to hold its current reading in memory even with main power off. This lets the robot resume from the exact position when power returns, without re-reading or recalibrating from scratch. That’s why the statement is true: during normal power-off, the backup batteries preserve the present reading. If there were no backup power, the reading could be lost, which is why the other options don’t fit—the retention isn’t limited to maintenance, nor conditional on the batteries merely being present; it relies on the backup energy being available to keep the data.