iDP3221User ’sManual
131 CITIZEN
2.3 Precautions
1) The Negotiation phase is triggered with the rising edge of the IEEE 1284 Active signal sent by the host.
2) In Compatibility mode, the time when the negotiation process begins is, as a general rule, after the host sets
nStrobe toH ighand 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 isdetected, 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 theC ompatibilitymode. In this case, the printer
will not return to the Busy or Error state it was in before the negotiations, but will remain in the printer state it
was inafter Termination.
4) If the host requested a communication mode that is not supported by the printer, it must move into the
Terminationphase and return to the Compatibility mode.
Table2.4.1 Definitions of Request Bits in IEEE 1284 Communication Mode
Xflag
Bit Definition BitValues
(76543210) Hex. When
supported Inthe
printer
7RequestExtensibility Link 10000000 80H High Low
6RequestEPP Mode 01000000 40H High Low
5RequestECP Mode with RLE 00110000 30H High Low
4RequestECP Mode 00010000 10H High Low
3Reserve 00001000 08H High Low
2 RequestDevice ID: Return Data Using
Nibble Mode Rev Channel Transfer
Byte Mode Rev Channel Transfer
ECP Mode Transferwithout RLE
ECP Mode Transfer withRLE
00000100
00000101
00010100
00110100
04H
05H
14H
34H
High
High
High
High
High
High
Low
Low
1Reserve 00000010 02H High Low
0ByteMode Reverse Channel Transfer 00000001 01H High Low
None NibbleMode Reverse Channel Transfer 00000000 00H Low Low
Illegalo r ContradictoryReq uest Other thanabove Other than
above Low
Note: The printer only supports the Nibble and Byte modes. For a request for any other mode, Xflag is set to Low.