1. ZPL II, ZBI 2, Set-Get-Do, Mirror, WML Programming Guide
  2. Error Detection Protocol
  3. Response From the Zebra Printer
  4. How the Zebra Printer Processes a Request Packet
  • ZPL II, ZBI 2, Set-Get-Do, Mirror, WML Programming Guide
How the Zebra Printer Processes a Request Packet

How the Zebra Printer Processes a Request Packet

The following describes the steps taken at the Zebra printer to process a Request Packet.
  1. The Zebra printer looks for a SOH (Start of Header) character. As soon as it finds one, it places the SOH and all the data after it into its Receive Data Buffer. This process continues until the printer receives an EOT (End of Transmission) character.
    If a second SOH is received before an EOT is detected, the contents of the Receive Buffer will be discarded. All of the data after the second SOH will be placed in the Receive Data Buffer.
  2. After detecting the EOT, the printer checks for the following:
    * The DST. Z-ID matches the printer’s Network I.D.
    If the Network ID at the printer is all zeros, the printer will accept all Request Packets regardless of the DST. Z-ID received. If a Request Packet is received with the DST. Z-ID all zeros, it is accepted by all printers regardless of their Network ID setting.
    *The Data Format begins with STX and ends with ETX.
    *The Sequence Number has not been used before.
    If the check is satisfactory, proceed to Step 3 on the following page.
    If any part of the check is unsatisfactory, the printer discards the data in its Receive Data Buffer and waits for another SOH. No response is sent to the computer.