Nellcor N-200 Operator's Manual page 60

Guide to Operation
The host device can send one of three commands:
Command:
Device Sends:
N-200 Responds: < STX > W < CRLF > < ETX > — Sent once
A Z packet, followed by a number of W and Y packets. The
number of W packets is given by the first parameter Zn . . . n in
the Z packet plus one. The very last (Zn . . . n +1) W packet
sent is a guard packet (used for spacing graphics output). The
data in this last W-packet is invalid—discard them. Hence, Zn .
. . n gives the number of valid W packets or data points. If
events have occurred during the trend period, then Y packets
will appear spaced among the W packets at the time that the
events occurred. The Y packets are not included in the Zn . . . n
count.
Command:
Device Sends:
N-200 Responds: < STX > X < CRLF > < ETX > — Sent once
*Note: Square brackets indicate optional items.
54
SEND TREND
W< CRLF >
when command received.
Z, W, [Y] *
< STX > E < CRLF > < ETX > — End of data,
normal completion
SEND EVENTS
X < CRLF >
when command received.
Z, X, [Y] *