Zebra TTPM2 Specifications download pdf (Page 52)

Command Reference

Magnetic Encoding- and Decoding-Related Commands

P1003645-001 TTPM2™ Installation and Programming Manual 03/05/2009

Figure 19 • This figure shows which characters can be coded with the different

coding formats

Checksum

To ensure correct reception of the message to be magnetically encoded, a checksum can be

appended to the data by the host computer. This checksum will then be compared by the

TTPM2 before encoding which guarantees that the magnetic code data is correctly received.

Calculate the checksum as the modulo 2 sum (consecutive XOR) of the ASCII data bytes sent

in the !M command. The checksum must have bit 7 set to 1 to distinguish it from ordinary

data.

Append the checksum at the end of the !M data string when encoding ISO data at track 2 (or

center track).

When the message has been received, the TTPM2 calculates the checksum and compares it to

the checksum appended to the message. If they are identical, an ACK is returned, otherwise a

NAK followed by the checksum calculated by the TTPM2 will be returned.

The checksum is never encoded on the magnetic stripe; it is only intended to secure data

transmission. The ISO format itself automatically adds a check digit to the magnetic code.

Note • With HiCo encoding, only one track at a time can be used for encoding or reading. In

this case, code first track with | or $ in the magnetic string to return the ticket to active

position after coding, then reset the printer with !C, and code the other track and print the

ticket.

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Zebra TTPM2 Specifications Page 52