USTER HVI 900 - Page 288

USTER® HVI 900 Instruction Manual
Uster Technologies, Inc. Chapter 14
Version 4.0 (1.99) Appendix - Page 14-22
Note that <CR> in the above example is a single character, namely CR
(0xd), at the end of this record. The 21 in the last field is the checksum
derived by taking the xor of the 47 characters before the "53."
Interaction between instrument and external computer (transmission
cycle):
• HVI will send a ready-for-transmit record upon entry into system
testing.
• Only an ACK (0x06) is necessary as a reply.
Instrument will send a start-dataset record (see record types below)
before the first data record of a sample.
• Instrument will send a stop-dataset record after testing for a
particular sample is complete and all data records for that
sample have been sent and acknowledged.
• HVI will expect to receive an ACK (0x06) upon good transmission of
record.
• Instrument will expect to receive a NAK (0x15) upon bad
transmission of record.
• Instrument will attempt three transmissions while receiving a NAK
before failing this transmission cycle.
•
HVI will wait some amount of time after transmission for a signal
from the external computer. The amount of this time will be set in the
Status Menu. After this time has expired, this transmission cycle will
fail.
• Upon failure of the transmission-response sequence, the instrument
will query the operator to either retransmit or abort. Abort will cause
control of the instrument to return to the menu prior to sample testing.