D440IS
2-36
10.4.29 Lock keypad
LK<CR>
Only the keypad is locked and the terminal displays the message
"
KEYLOCK
".
10.4.30 Unlock keypad
UK<CR>
The keypad is unlocked.
10.4.31 Remote commands with checksum
Management of remote commands with checksum can be enabled
during the installation phase (par. 11.6.14 on page 2-74).
Checksum mode increases security when the terminal and PC dialogue
with each other since the following precautions are taken:
✔
each remote command transmitted to the terminal must contain two
checksum characters in a dedicated position;
✔
each reply with data that the terminal transmits to the PC after a
remote command must contain two checksum characters in a
dedicated position.
The position of the two checksum characters is immediately prior to the
<CR> character..
Checksum calculation involves making the XOR (exclusive OR) of all the
characters in the string up to the first checksum character excluded. The
result is expressed by two hexadecimal characters.
An example of a gross weight transmission with checksum is given
below:
XB chk1chk2 <CR>
where, supposing that value 1A is obtained from XOR:
chk1 is the first checksum character ("1" or rather 31H)
chk2 is the second checksum character ("A" or rather 41H).
The terminal replies with the following string:
n<SP><um><SP>B chk1chk2 <CR><LF>
Summary of Contents for D440IS
Page 1: ...Terminal D440IS Advanced user manual Code 81320155 EDITION 08 06 2015 ...
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