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CM4 Protocol Manual
ACK/NAK Handshake
Each slave (CM4) uses a handshake scheme between itself
and the master. The simplest response back from the
instrument is called an ACK (an abbreviation for
ACKnowledge). When the slave receives a command packet
from the equipment, it will send back an ACK response if
the command is received, but no additional data has been
requested in the command.
If however, the checksum does not match, the slave will send
a NAK (an abbreviation for Negative AcKnowledge). A NAK
indicates that a data packet has been received, but the
checksum did not match with the packet data. The master
may send the request again. An example of an ACK packet
is 0x40, 0x00, 0x05, 0x20, 0x9B (40 + 0 + 5 + 20
+ 9B = 0x100).
7
Rev. 2.4 (3/05)
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