OHAUS Aviator 7000 Series, Руководство по обслуживанию

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Service Manual
Page 38 of 50
6.1.2.4 Command Flow
ECR Scale COMMENTS
ENQ (05h)
ACK (06h)
Data Available.
Errors could be:
CAN - repeat weighing
NAK - no acknowledgement
NUL - no data available
DC1 (11h)
Data Request
Errors could be:
NAK
– no acknowledgement
STX ID W5W4W3W2W1 BCC ETX Transmitted Data
STX ID W5W4W3W2W1 BCC ETX
Confirm Data
Errors could be:
ACK
– Data not confirmed
CR (0dh) Data confirmed
Note: Spaces depicted in the description above are only used for ease of reading. No space
characters are used unless the BCC result yields the space character.
6.1.3 Dialog 06
With free programmable POS-Systems it is for a third party on principle possible, to manipulate parts of
the software, which are obligate to verification.
For this reason certifying agencies expects appropriate protection against such inadmissible manipulations
of third parties.
A protection against manipulations presents the Checkout-Dialogue 06 in conjunction with precautions
taken at the POS-Software.
6.1.3.1 POS-Software
The parts of the POS-Software, which are obligated to verify, have to be protected with checksums (here
called value CS), created by an appropriate method (for instance CRC16). These checksums CS have
also to be protected with checksums (here called value KW), created by the CRC16-method in use with a
polynomial P, which is known only by the manufacturers of the scale and the POS-system. CS and KW
both have a length of 16 bit.
REMARK: KW REPRESENTS THE REST OF THE POLYNOMIAL-DIVISION CS / P.
6.1.3.2 Checkout-Dialogue 06
The checkout-dialogue 06 presents for the scale the possibility, to request 1-5 pairs of values CS/KW in
cyclic intervals from the POS-system and check their validity. In case of invalidity, no weight-results will be
given from the scale to the POS-system, i.e. dealing with the scale is not possible. With the request for the
checksums, the scale sends a random number, which has to be used from the POS-system for encoding
the checksums. This shall prevent a third party from monitoring valid checksums with simple measures.
The random number is an 8-bit-number, the higher nibble (here called Z1) is used for encoding the
CS-values, and the lower nibble (here called Z2) is used for encoding the KW-values. The encoding of the
CS-values has to be made by rotating them to the left for Z1 bits, the encoding of the KW-values by
rotating them to the right for Z2 bits.
For checking the conformity of the used protocol version in POS-system and scale, the Checkout-Dialogue
06 presents for the POS-system the possibility to order the scale to display the version number of the
protocol. If the POS-system also displays the version number, the conformity can be checked.