EasyCoder 3400e Bar Code Label Printer User’s Manual
When the printer returns Buffer Now Full (<DC3>) status, it accepts the currently received message block. At this time, the printer can accept short messages to allow parsing of immediate commands such as Reset (<DLE>) or Cancel Batch Printing (<EM>). However, if the printer responds with a <GS> to any message block, the buffer is already full and the printer discards the entire message block.
XON/XOFF Protocol (Software and Hardware Flow Control)
The XON/XOFF protocol stops the host from sending data when the printer buffer fills up and starts the host again when the buffer empties. When you select this protocol, you concurrently enable software and hardware flow control. Software flow control uses the ASCII characters <DC1> (XON) and <DC3> (XOFF) to start and stop the flow of data from the host to the printer. Hardware flow control uses pin 11 or pin 20 (internally connected together) on the printer’s serial port to indicate “Ready” or “Busy” for data flow control. As with Standard protocol, <STX> and <ETX> enclose data. Status responses conform to the table above except that <DC2> is substituted for <DC1> and <DC4> is substituted for <DC3>.
The printer does not restrict the message length for XON/XOFF protocol. That is, the printer processes information as it is being downloaded and stops when there is no more information. There is no restriction on the number of characters that can be sent down at a time. <STX> and <ETX> are optional characters.
Pin 11/20 reports “Ready” and a <DC1> (XON) is transmitted when the printer finishes reloading at
Pin 11/20 becomes “Ready” when the printer has transferred all the data from the input buffer. If the printer receives a <DC3>, it transmits a <DC1> (XON) and the host may resume transmission. When you switch the printer offline, pin 11/20 becomes “Busy” and it transmits a <DC3>. When you switch the printer online (and the input buffer is empty), pin 11/20 becomes “Ready” and it transmits a DC1.
