Star Micronics RS232 manual goes LOW to trigger data read

Pin no	Signal name			Direction	Function
1				IN	Strobe pulse for data read. Usually HIGH;
		STROBE
					goes LOW to trigger data read.
2-9	DATA 1~8			IN	Parallel data lines for eight-bit data. HIGH
					is “1”; LOW is “0”.
10				OUT	Printer outputs this pulse for approxi-
			ACK
					mately 9μs to indicate that data read is
						PARALLEL
					completed. Printer becomes ready to
					receive new data at the moment the ACK
					pulse ends.
11		BUSY		OUT	DC-level signal indicating printer’s cur-
					rent status. LOW indicates that printer is
					ready to receive the next data; HIGH
					indicates that printer is unable to receive.
12		PAPER OUT		OUT	DC-level signal indicating whether printer
					has paper. The signal stays LOW while paper
					is present; it goes HIGH to indicate that paper
					has run out.
13		SELECTED		OUT	DC-level signal; stays HIGH while printer is
					online.
14-15	N/C				Not used
16		SIGNAL GND			Signal ground
17		CHASSIS GND			Printer-frame ground
18		+5V			Outputs +5V (Max. 50mA)
19-30	TWISTED				Return pins for various signals. Each pin is
		PAIR RETURN			connected to the corresponding signal line by
					twisted pair line.
31		RESET		IN	LOW level causes printer to reset its control
					circuitry and return to its initial state.
32				OUT	Goes LOW to indicate that printer is unable to
		ERROR
					print.
33		EXT GND			Ground terminal for external connection
34-35	N/C				Not used
36		–		–	Fixed “HIGH” at printer side

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