- 503 -
Precautions
(1) The Negotiation phase is triggered when the IEEE 1284 Active signal sent by the host becomes High.
(2) In Compatibility mode, the time when the negotiation process begins is, as a general rule, after the host sets nStrobe to High
and then the printer outputs an nAck pulse.
Once the nStrobe signal is set to High, however, the printer immediately moves into the Negotiation phase when the high
state of IEEE 1284 Active is detected, even if the nAck pulse has yet to be output or is being output. In this case, if the
printer has returned to Compatibility mode after Termination, no nAck pulse will be output.
(3) Negotiations can be entered from the Busy or Error state of the Compatibility mode. In this case, the printer will not return to
the Busy or Error state before the negotiations, but still remains in the printer state just after Termination.
(4) If the host requested a communication mode that is not supported by the printer, it must move into the Termination phase
and return to the Compatibility mode.
Table Definitions of Request Bits in IEEE 1284 Communication Mode
bit
Definition
Bit Values
(76543210)
Hex Code
Xflag
When Supported
In the Printer
7
Request Extensibility Link
10000000
80H
High
Low
6
Request EPP Mode
01000000
40H
High
Low
5
Request ECP Mode with RLE
00110000
30H
High
Low
4
Request ECP Mode
00010000
10H
High
Low
3
Reserve
00001000
08H
High
Low
2
Request Device ID:Return Data Using
Nibble ModeRev Channel Transfer
Byte Mode Rev Channel Transfer
ECP Mode Transfer without RLE
ECP Mode Transfer with RLE
00000100
00000101
00010100
00110100
04H
05H
14H
34H
High
High
High
High
High
High
Low
Low
1
Reserve
00000010
02H
High
Low
O
Byte Mode Reverse Channel Transfer
00000001
01H
High
High
non Nibble Mode Reverse Channel Transfer
00000000
00H
Low
Low
Illegal or Contradictory Request
Other than
above
Other than
above
--
Low
The printer only supports the Nibble and Byte modes. For a request for any other mode, Xflag is set to Low.
*Remarks: CT-P29x series support Nibble Mode only.
