Device ID
The device ID is a character string that provides the ID, the type, and other information regarding the printer connected to the interface. When the printer receives a request for a device ID from the host, it replies with the following device ID:
<00>H<2E>H MFG : CBM; CMD : ESC/POS; MDL :
CLS : PRINTER;
The first two bytes of the device ID indicate the length of the entire device ID. For a description of a request for a device ID, refer to the “Negotiation” section.
When the host receives the device ID string of the length indicated by the first two bytes, it must do so consecutively, without terminating the process until the entire device ID is received. If the process is terminated halfway, the printer discards the rest of the string; when the printer receives a new request for the device ID, it sends the device ID beginning from the first character of the ID. After receiving the ID of the length indicated by the first two bytes, the host must carry out the termination even if the printer has data to send (Data Available). If the host does not carry out Termination and tries to receive data, the printer sends the printer status.
Termination
Termination is the process of returning to Compatibility mode from the Nibble or Byte modes. When performing Termination, the host sets the signals as follows:
•IEEE 1284 Active (nSelectln): Low
•HostBusy (nAutoFd): High (Event 22)
There are two methods of Termination:
(1)Termination through a handshake between the host and the printer
(2)Immediate termination
(1)Termination through a handshake between the host and the printer:
When switching from Reverse mode to Compatibility mode, this termination method can be used if the interface is activated (IEEE 1284 Active: High) and Event 22 has taken place.
1)The printer responds to IEEE 1284 Active by setting PtrBusy (Busy) and nDataAvail (nFault) to High. (Event 23)
2)The printer then inverts Xflag (Select) and sets PtrClk (nAck) to Low. (Event 24)
3)The host sets HostBusy (nAutoFd) to Low. (Event 25)
4)The printer returns nDataAvail (nFault), Xflag (Select), and AckDataReq (PError) to the status given in the Compatibility mode, and sets PtrClk (nAck) to High. (Events 26 and 27)
5)The host sets HostBusy (nAutoFd) to High to terminate the handshake and return the interface to the Compatibility Mode Idle phase. (Event 28)
6)The printer changes PtrBusy (Busy) to be able to receive data from the host.
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