System for recognizing bidirectional communication over parrallel data lines by further sending data transmission request and notification indicating reverse direction transmission is possible to second device

• US 6,014,716 A
• Filed: 06/27/1997
• Issued: 01/11/2000
• Est. Priority Date: 07/01/1996
• Status: Expired due to Term

• Current Assignee: Brother Kogyo Kabushiki Kaisha (Brother Industries Limited)
• Original Assignee: Brother Kogyo Kabushiki Kaisha (Brother Industries Limited)
• Inventors: Ohara, Kiyotaka
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): Park, Ilwoo
• Application Number:
  US08/884,474
• Time in Patent Office: 928 Days
• Field of Search: 395/182.16, 395/185.05, 395/821, 395/115, 395/114, 395/200, 395/239.9, 395/241.9, 395/280, 395/884, 600/508, 400/708, 400/64, 371/37.6, 371/37.7, 371/53, 711/172, 364/927.8, 710/8, 710/12, 710/14, 710/31
• US Class Current: 710/14
• CPC Class Codes: G06F 13/4269 using a handshaking protocol, e.g. Centronics connection

Abstract

A bidirectional communication method, bidirectional communication device and storage medium for automatically setting the communication mode without complications to the user and not causing the malfunctioning of the computer system and the printer are disclosed. The control register of the personal computer is used to set data reception from the laser printer in a byte mode. A specific data is written to the data register, and the value of the data register is read. If the value of the data register is not the specific data, it is recognized that the personal computer can be set to the byte mode. If, on the other hand, the read value of the data register is the specific data, another specific data is written to the data register, then the value of the data register is read, and if the value of the data register is another specific data, it is recognized that the personal computer cannot be set to the byte mode.

Claims

1. A bidirectional communication recognition method for a first device in a communication system for transmitting data in a forward direction from the first device to a second device over parallel data lines of a parallel interface, and transmitting data in a reverse direction from the second device to the first device over the parallel data lines, the method comprising:

writing specific data to a data register provided in the first device, which outputs data written during forward direction transmission as parallel signals to the parallel data lines,

reading contents of the data register, and

comparing the written specific data with the read contents to determine whether the read contents and the written data are different,

if the read contents and the written data are determined to be different, recognizing that bidirectional communication of the first device and the second device at a predetermined system over the parallel data lines is possible without operator intervention,

if the read contents and the written data are determined to be identical recognizing that the bidirectional communication is not possible without operator intervention, and

when the read contents and the written data are determined to be different, sending a data transmission request and a notification indicating that data line reverse direction transmission is possible from said first device to said second device.

2. The bidirectional communication recognition method according to claim 1, said first device comprising a computer system and said second device comprising a printer.

3. The bidirectional communication recognition method according to claim 1, further comprising:

constantly changing a content of said specific data until the read contents and the written data are determined to be different, the writing of said specific data and the reading of the contents of the data register being performed repeatedly a specific number of times as an upper limit, and

if after the writing of the specific data and the reading of the contents of the data register are performed repeatedly the specific number of times and the read contents and the written data are not determined to be different, recognizing that the bidirectional communication is not possible.

4. The bidirectional communication recognition method according to claim 1, further comprising:

when the read contents and the written data are determined to be different, sending a notification indicating that data line reverse direction transmission is possible from said first device to said second device,

if a signal indicating that the data line reverse direction transmission is not possible is not returned from the second device over control lines of the parallel interface to the first device in response to the notification, recognizing that said bidirectional communication is possible, and

if a signal indicating that the data line reverse direction transmission is not possible is returned from the second device over the control lines of the parallel interface to the first device in response to the notification, recognizing that the bidirectional communication is not possible.

5. The bidirectional communication recognition method according to claim 1,

if data returned from the second device by the data line reverse direction transmission in response to the data transmission request is correct, recognizing that said bidirectional communication is possible, and

if the return data is not correct, recognizing that the bidirectional communication is not possible.

6. The bidirectional communication recognition method according to claim 1, further comprising:

when the read contents and the written data are determined to be different, sending a data transmission request and a notification indicating that data line reverse direction transmission is possible from said first device to said second device,

if a signal indicating that the data line reverse direction transmission is not possible is not returned from the second device over control lines to the first device in response to the notification, and if data returned by the data line reverse direction transmission from the second device in response to the data transmission request is correct, recognizing that the bidirectional communication is possible, and

if a signal indicating that the data line reverse direction transmission is not possible is returned from the second device over the control lines to the first device in response to the notification, or if the data returned by the data line reverse direction transmission from the second device in response to the data transmission request is not correct, recognizing that the bidirectional communication is not possible.

7. The bidirectional communication recognition method according to claim 6, further comprising, if said bidirectional communication is recognized not to be possible, recognizing that, for parallel reverse direction transmission of data from the second device to the first device, only control line reverse direction transmission using a plurality of control lines in parallel is possible.

8. The bidirectional communication recognition method according to claim 7, further comprising:

if said bidirectional communication is recognized to be possible, setting said first device to perform bidirectional communication, and

if said bidirectional communication is recognized not to be possible, setting the first device to perform bidirectional communication comprising forward direction communication and said control line reverse direction transmission using a plurality of control lines in parallel.

9. The bidirectional communication recognition method according to claim 1, further comprising:

when said bidirectional communication is determined not to be possible, sending a notification indicating that control line reverse direction transmission using a plurality of control lines in parallel is possible from said first device to said second device, and wherein,

if a signal indicating that the control line reverse direction transmission is not possible is not returned from the second device to the first device over control lines of the parallel interface in response to the notification that the control line reverse direction transmission is possible, recognizing that the control line reverse direction transmission is possible, and

if a signal indicating that the control line reverse direction transmission is not possible is returned from the second device to the first device over the control lines in response to the notification that control line reverse direction transmission is possible, recognizing that the control line reverse direction transmission is not possible.

10. The bidirectional communication recognition method according to claim 1, further comprising:

when said bidirectional communication is determined not to be possible, sending a notification indicating that control line reverse direction transmission using a plurality of control lines in parallel is possible and a data transmission request from the first device to the second device,

if data returned in response to the data transmission request from the second device by control line reverse direction transmission is correct, recognizing that the control line reverse direction transmission is possible, and

if the returned data is not correct, recognizing that the control line reverse direction transmission is not possible.

11. The bidirectional communication recognition method according to claim 1, further comprising:

when said bidirectional communication is determined not to be possible, sending a notification indicating that control line reverse direction transmission using a plurality of control lines in parallel is possible and a data transmission request from the first device to the second device,

if a signal indicating that the control line reverse direction transmission is not possible is not returned from the second device to the first device over the control lines in response to the notification, and if data returned in response to the data transmission request from the second device by the control line reverse direction transmission is correct, recognizing that the control line reverse direction transmission is possible, and

if a signal indicating that the control line reverse direction transmission is not possible is returned from the second device to the first device over the control lines in response to the notification, or if the data returned in response to the data transmission request from the second device by control line reverse direction transmission is not correct, recognizing that the control line reverse direction transmission is not possible.

12. The bidirectional communication recognition method according to claim 11, further comprising:

if said control line reverse direction transmission is recognized not to be possible, recognizing that parallel reverse direction transmission of data from the second device to the first device is not possible.

13. The bidirectional communication recognition method according to claim 12, further comprising:

if said control line reverse direction transmission is recognized to be possible, setting said first device to perform the control line reverse direction transmission, and

if the control line reverse direction transmission is recognized not possible, setting the first device to perform neither said bidirectional communication nor the control line reverse direction transmission.

14. The bidirectional communication recognition method according to claim 13, said first device and said second device independently comprising a byte mode or a nibble mode.

30. A storage medium for storing a program implementing the bidirectional communication method according to claim 1, said program being implemented at said first device as a computer system.

31. The storage medium according to claim 30, the second device comprising a printer.

15. A bidirectional communication recognition device in a communication system for transmitting data in a forward direction from a first device to a second device over parallel data lines of a parallel interface, writing data to a data register provided at the first device, and outputting the data as parallel signals to the parallel data lines, the bidirectional communication recognition device comprising:

reverse direction transmission setting means that sets a data line reverse direction transmission for transmitting data from the second device to the first device over the parallel data lines,

data register write/read means that writes specific data to the data register and reads contents of the data register after the data line reverse direction transmission has been set by the reverse direction transmission setting means,

comparing means that compares two values including a value of specific data written by the data register write/read and a value of the contents read by the data register write/read means, and determines whether or not the two values are identical,

recognition means that recognizes that bidirectional communication over the parallel data lines between the first device and the second device is possible if the comparing means determines that the two values are different without operator intervention, and recognizes that the bidirectional communication over the parallel data lines between the first device and the second device is not possible if the comparing means determines that the two values are identical without operator intervention and

notifying means that sends a notification indicating that data line reverse direction transmission is possible from said first device to said second device when said comparing means determines that the data line reverse direction transmission is not possible has been returned from the second device over control lines of the parallel interface.

16. The bidirectional communication recognition device according to claim 15, said bidirectional communication recognition device being provided in the first device.

17. The bidirectional communication recognition device according to claim 15, said first device comprising a computer system and said second device comprising a printer.

18. The bidirectional communication recognition device according to claim 15,

said comparing means causing said data register write/read means to repeatedly change a content of the specific data, write the specific data and read the contents of the data register a specified number of times as an upper limit until the two values are determined to be different, and

said recognition means recognizing that said bidirectional communication is possible if the comparing means determines that said two values are different, or that said bidirectional communication is not possible if the comparing means cannot determine that the two values are different even after the data register write/read means has written the specific data and read the contents of the data register the specified number of times.

19. The bidirectional communication recognition device according to claim 15,

said recognition means recognizing that the bidirectional communication is possible if a reply indicating that the data line reverse direction transmission is not possible has not been detected by reply detecting means when the comparing means determines that the two values are different, or that the bidirectional communication is not possible if a reply indicating that the data line reverse direction transmission is not possible has been detected by the reply detecting means.

20. The bidirectional communication recognition device according to claim 15, further comprising:

data transmission request means that sends a notification indicating that data line reverse direction transmission is possible and a data transmission request from said first device to said second device when said comparing means determines that said two values are different, and

data status detecting means that detects whether or not data returned in response to the data transmission request by the data transmission request means from the second device by said data line reverse direction transmission is correct,

said recognition means recognizing that the bidirectional communication is possible if the data status detecting means detects that data returned by the data line reverse direction transmission is correct when the comparing means determines that the two values are different, or that the bidirectional communication is not possible if the data status detecting means detects that the data returned is not correct.

21. The bidirectional communication recognition device according to claim 15, further comprising:

data transmission request means that sends a notification indicating that data line reverse direction transmission is possible and a data transmission request from said first device to said second device when said comparing means determines that said two values are different,

reply detecting means that detects whether or not, in response to the notification of the data transmission request means, a signal indicating that the data line reverse direction transmission is not possible has been returned from the second device over control lines, and

data status detecting means that detects whether or not data returned, in response to the data transmission request by the data transmission request means, from the second device by the data line reverse direction transmission is correct,

said recognition means

     1) recognizing that the bidirectional communication is possible, if a reply indicating that the data line reverse direction transmission is not possible has not been detected by reply detecting means, and if the data status detecting means detects that the data returned by data line reverse direction transmission is correct when the comparing means detects that the two values are different, or

     2) recognizing that the bidirectional communication is not possible if a reply indicating that the data line reverse direction transmission is not possible has been detected by the reply detecting means or if the data status detecting means detects that the data returned by the data line reverse direction transmission is not correct.

22. The bidirectional communication recognition device according to claim 21, if said recognition means recognizes that said bidirectional communication is not possible, said recognition means recognizing that for parallel reverse direction transmission of data from said second device to said first device, only control line reverse direction transmission using a plurality of control lines in parallel is possible.

23. The bidirectional communication recognition device according to claim 22, if said recognition means recognizes that said bidirectional communication is not possible, said recognition means setting said first device to perform the bidirectional communication, and

if said recognition means recognizes that the bidirectional communication is not possible, said recognition means setting the first device to perform the bidirectional communication comprising forward direction communication and said control line reverse direction transmission using the plurality of control lines in parallel.

24. The bidirectional communication recognition device according to claim 21, the recognition means comprising a first recognition means, the device further comprising:

second notifying means that sends a notification indicating that control line reverse direction transmission using a plurality of control lines in parallel is possible from said first device to said second device when said first recognition means recognizes that said bidirectional communication is not possible,

second reply detecting means that detects whether or not, in response to the notification by the second notifying means, a signal indicating that control line reverse direction transmission is not possible has been returned from the second device over said control lines of the parallel interface, and

second recognition means that recognizes that control line reverse direction transmission is possible if a reply indicating that control line reverse direction transmission is not possible has not been detected by second reply detecting means, and that recognizes that the control line reverse direction transmission is not possible if a reply indicating that the control line reverse direction transmission is not possible has been detected by the second reply detecting means when the first recognition means recognizes that bidirectional communication is not possible.

25. The bidirectional communication recognition device according to claim 21, the recognition means comprising a first recognition means, the device further comprising:

second data transmission request means that sends a notification indicating that control line reverse direction transmission using a plurality of control lines in parallel is possible and a data transmission request from said first device to said second device when said first recognition means recognizes that said bidirectional communication is not possible,

second data status detecting means that detects whether or not data returned in response to the data transmission request by the second data transmission request means from the second device by said control line reverse direction transmission is correct, and

second recognition means that recognizes that the control line reverse direction transmission is possible if the second data status detecting means detects that the data returned by the control line reverse direction transmission is correct, or that recognizes that the control line reverse direction transmission is not possible if the second data status detecting means detects that the returned data is not correct when the first recognition means recognizes that the bidirectional communication is not possible.

26. The bidirectional communication recognition device according to claim 21, the recognition means comprising a first recognition means, the device further comprising:

second data transmission request means that sends a notification indicating that control line reverse direction transmission using a plurality of lines in parallel is possible and a data transmission request from said first device to said second device when said first recognition means recognizes that said bidirectional communication is not possible,

second reply detecting means that detects whether or not, in response to the notification by the second data transmission request means, a signal indicating that the control line reverse direction transmission is not possible has been returned from the second device over control lines of the parallel interface,

second data status detecting means that detects whether or not data returned in response to the data transmission request by the second data transmission request means from the second device by the control line reverse direction transmission is correct, and

second recognition means that recognizes that the control line reverse direction transmission is possible if a reply indicating that the control line reverse direction transmission is not possible has not been detected by second reply detecting means, and that recognizes that the control line reverse direction transmission is not possible if the second data status detecting means detects that data returned by the control line reverse direction transmission is correct when the first recognition means recognizes that the bidirectional communication is not possible, or that recognizes that the control line reverse direction transmission is not possible if a reply indicating that the control line reverse direction transmission is not possible has been detected by second reply detecting means or if the second data status detecting means detects that the data returned by control line reverse direction transmission is not correct.

27. The bidirectional communication recognition device according to claim 26,

if said second recognition means recognizes that said control line reverse direction transmission is not possible, said second recognition means recognizing that parallel reverse direction transmission of data from said second device to said first device is not possible.

28. The bidirectional communication recognition device according to claim 26,

if said second recognition means recognizes that said control line reverse direction transmission is possible, said second recognition means setting said first device top perform the control line reverse direction transmission, and

if said second recognition means recognizes that the control line reverse direction transmission is not possible, said second recognition means setting said first device to perform neither the bidirectional communication nor the control line reverse direction transmission.

29. The bidirectional communication recognition device according to claim 28, said first device and said second device independently comprising a byte mode or a nibble mode.