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Pressure Systems, Inc. NetScanner™ System (9016, 9021, & 9022) User’s Manual
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3 - 4
The channel data requested will always be returned in order of
highest requested channel to lowest requested channel.
channel is affected by the command. The least-significant (rightmost) bit 0 corresponds to Channel
1, and the most-significant (leftmost) bit 15 corresponds to Channel 16. Since neither model has
more than sixteen (16) channels, the position field will usually be 16-bits, represented by four (4)
ASCII-hex characters in the command. For example, only Channels 16 and 1 are selected below in
this 16-bit (4-character) position field:
Bit# 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Chan#
16
15 14 13 12 11 10 9 8 7 6 5 4 3 2
1
Binary 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
Hex 8 0 0 1
The above position field, with all applicable bits set (i.e., FFFF for 16-channel module), specifies
all channels. However, a module-independent variation allows a missing position field to designate
all channels — but only when there are no other parameters following the position field in the
command. For such commands, the hex position field may be reduced to 3, 2, or 1 characters when
no channel bits need be set (1) in the discarded high-order characters (nibbles).
3.1.2.4 Datum Fields
Any datum fields in a command generally contain data to be sent to the module, usually specified
by a position field bit map. In some commands (when data are received from a module instead) no
datum fields are required in the command itself but the position field bit map is still used to specify
the order that data are returned in the command’s response. In either case, the order bits are set (to
1) in the position field bit map (highest channel # to lowest channel#, left to right) is the order these
datum fields are received or sent.
Each datum field may be variable in length, whether part of the command itself or the command’s
response. In its most common format, a datum begins with a space character (‘ ’), and is followed
by an optional sign, decimal digits, and a decimal point, as needed (e.g., ‘ -vv.vvvvvv’). For other
formats it may be a hex digit string or pure binary number.