Citizen CBM1000 User Manual
—163 —
13.2.3 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.
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.
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.
mode.
Table 2.4.1 Definitions of Request Bits in IEEE 1284 Communication Mode
Xflag
Bit
Definition
Bit Values
Hex.
When
In the
(76543210)
supported 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
Request Device ID: Return Data Using
Nibble Mode Rev Channel Transfer
Nibble Mode Rev Channel Transfer
00000100
04H
High
High
2
Byte Mode Rev Channel Transfer
00000101
05H
High
High
ECP Mode Transfer without RLE
00010100
14H
High
Low
ECP Mode Transfer with RLE
00110100
34H
High
Low
1
Reserve
00000010
02H
High
Low
0
Byte Mode Reverse Channel Transfer
00000001
01H
High
High
None Nibble Mode Reverse Channel Transfer 00000000
00H
Low
Low
Illegal or Contradictory Request
Other than Other than
—
Low
above
above
Note: The printer only supports the Nibble and Byte modes. For a request for any
other mode, Xflag is set to Low.