Printronix p300 Maintenance Manual page 58

2–6. Paper Feed State
a. General
–continued
Paper Motion Detection Logic
Paper Feed Control Circuits
The paper feed state is terminated when the PPF flip–flop is reset with an end paper feed pulse, EPFP, at the
end of paper motion generated when the following conditions exist:
–The final paper feed pulse pair, PF1/PF2 has been sent to the motor drive circuits on the power supply
PCBA.
–Slew NSLW is inactive.
–The row counter reset pulse, NRCR, occurs.
b. Paper Feed to Next Dot Row (Figure 2–23)
During the print state, paper is advanced to the next row within the character line when early paper move,
NEMOV, goes low. NEMOV is generated by dot column logic and causes the following two events to
occur:
–Paper feed pulse, PF1, is generated.
–The velocity counter begins counting S5 pulses, each having a 16 microsecond duration.
The count of S5 pulses accumulates in the velocity counter. When the count reaches 182, the velocity
counter is reset, and paper feed pulse, PF2, is generated, advancing the paper one dot row.
The printer remains in the print state until the last dot row of the characters has been printed. The EOL
terminates the print state and initiates the paper feed state.
c. Paper Feed to Next Character Line (Figure 2–23 through Figure 2–25)
Paper is always moved by dot rows, with the dot row counter keeping track of the paper position.
When PPF is set by EOP, the count enable flip–flop enables the step counter which then counts RCLK
pulses and addresses the velocity PROM containing the number of steps in the acceleration and decelera-
tion profiles.
As the count of RCLK pulses increments to 12 (nine at eight lines per inch), each count selects the rate at
which paper feed pulses are generated during the next dot row period. The velocity counter counts the 16
microsecond S5 pulses and applies a binary coded address to the velocity PROM. The addressed velocity
PROM contents determine the rate at which paper feed pulses are generated during the current period.
2–36
–continued
ELEMENT SUBPARAGRAPH
P300/P600 Principles of Operation
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