User's Manual

14 485SDA103798 Manual
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The Read A/D channels command returns two bytes for each
channel read. The two bytes represent the most significant byte
(MSB) and least significant byte (LSB) of the reading. The MSB is
received first, followed by the LSB. This command requires a data
byte. The data byte is used to specify the number of the highest
channel to be read. All channels less than this channel will be read
as well. For example, if the data byte has a value of 6, then
channels 0 to 6 will be read. The highest channel is read first.
Command Syntax
!{addr}RA{#}
Where “{#}” is a byte that specifies the number of the highest
channel to be read. See Table 3.3
Response Syntax
{ch(#)MSB}{ch(#)LSB}{ch(#-1)MSB}...{ch0MSB}{ch0LSB}
The most significant byte of the channel specified is received first.
The least significant byte and the lower channels will follow in
descending order. “{chxMSB}” and “{chxLSB}” represent the most
and least significant bytes of the A/D conversion result.
NOTE: There are three test channels that can be read: Ref+, Ref-,
and Ref+/2. Specify 13 (0Dh) to read Ref+, 12 (0Ch) to read Ref-,
and 11 (0Bh) to read Ref+/2.
Table 3.3 - Read A/D Response
# of Channels Specified Response
decimal Hex ASCII
Channels Returned
(order of response)
Bytes
Returned
0 0 NUL Channel 0 2
1 1 SOH Channels 1,0 4
2 2 STX Channels 2,1,0 6
3 3 ETX Channels 3,2,..,0 8
4 4 EOT Channels 4,3,..,0 10
5 5 ENQ Channels 5,4,..,0 12
6 6 ACK Channels 6,5,..,0 14
7 7 BEL Channels 7,6,..,0 16
8 8 BS Channels 8,7,..,0 18
9 9 HT Channels 9,8,..,0 20
10 A LF Channels 10,9,..,0 22