220-801 · Question #1062
A technician has installed a serial printer on a PC in the shipping department. The printer self test ran without error. The user states that printed documents include many wrong characters. Which…
The correct answer is C. Change the printer communication speed to the port setting speed. Serial communication requires matching baud rate settings between the printer and the serial port. A mismatch causes garbled or incorrect characters to print, even if the printer's internal self-test passes.
Question
A technician has installed a serial printer on a PC in the shipping department. The printer self test ran without error. The user states that printed documents include many wrong characters. Which of the following should be performed to correct this problem?
Options
- AReplace the printer I/O logic and run the printer self test again.
- BReplace the printer cable and reset the printer to factory defaults.
- CChange the printer communication speed to the port setting speed.
- DChange the Parity to eight bit even and one stop bit.
How the community answered
(38 responses)- A3% (1)
- B13% (5)
- C76% (29)
- D8% (3)
Why each option
Serial communication requires matching baud rate settings between the printer and the serial port. A mismatch causes garbled or incorrect characters to print, even if the printer's internal self-test passes.
The self-test passing confirms the printer's internal I/O logic is functional, so replacing it would not address a speed mismatch issue.
Replacing the cable addresses physical signal integrity, not a logical baud rate mismatch, and factory defaults would not necessarily match the port speed.
Serial ports communicate using specific speed settings (baud rate) that must match on both ends of the connection. When the PC port and printer are configured to different speeds, data bits are misinterpreted, resulting in wrong characters on printed output. Changing the printer's communication speed to match the port setting resolves the mismatch.
Standard serial communication uses 8 data bits, no parity, and 1 stop bit (8N1); changing parity to even would introduce a different mismatch rather than correcting the speed problem.
Concept tested: Serial port baud rate mismatch troubleshooting
Source: https://learn.microsoft.com/en-us/windows-hardware/drivers/serports/configuration-of-com-ports
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