Printronix SL5000r MP Splitting the EPC, Verify Command is not Rfid Specific, Customer Scenario

The VERIFY Command is not RFID Specific

The VERIFY Command is not RFID Specific

Although the VERIFY command was added to PGL to enable the sending of RFID data back to a host, it is not actually an RFID command, since:

1.It does not cause any RFID activity

2.It is not restricted to RFID data.

The VERIFY command can be used to send any data expressed in a variable (such as bar code data) back to a host.

Splitting the EPC

Customer Scenario

The customer intended to write 362501031109 to the tag as a decimal number, but when they read the tag back they received 155693006861632597 (not what they expected).

Here Is What They Did

RFWTAG;96

64;D;*36250103*

32;D;*1109*

STOP

The problem is the way in which the decimal number was divided up. Position matters in arithmetic. One cannot ignore the implied leading zeros in the 32bit quantity as they are significant when the 64 bit value is non zero.

For example, 002000 is the same value as 2000, since the leading two zeroes are insignificant. However, 2002 is not the same as 22, since the zeroes are significant.

So when the customer chose 1109 as the LSB 32 bits, the leading zeros were padded to the left until 32 bits were filled, resulting in 00001109. This converted to hex so that 00000455 was written into those bits.

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