AMCI ANR2, Руководство пользователя

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Setting the Null Value (continued)
Channel Status Bits
Bits 8 and 9 in the Channel Status register can be used to determine if you are at the null point or the direction
of travel needed to reach it.
Table 7.3 Channel Status Bits - Setting Null Point
The Channel Status bits for channel 1 are in word 1 of the Network Input Data. The Channel Status bits for
channel 2 are in word 5 of the Network Input Data. A complete description of the
Channel Status Word For-
mat can be found on page 41.
Channel Position Value
The final way of determining the null point is to read the position value while aligning the sensor. The chan-
nel’s position value holds the raw ADC value in 32 bit sign-magnitude format. You can set the Null value
when the position reads within the range of ±255 counts. The position value for channel 1 is in words 2 and 3
of the Network Input Data. The position value for channel 2 is in words 6 and 7. A description of the
Net-
work Input Data format is started on page 37.
Set Null Value Command
Once you are at the null point of the sensor, write the following command to the ANR2 to set the position
value at this point.
Figure 7.2 Command Format: Set Null Value
ANR2 Response
The ANR2 response to a Set Null Value command by setting the Acknowledge Bit in the Module Status word
as well as the appropriate error code in bits 03 through 00 of that word. If the command is accepted without
error, the four error bits will equal zero. See
Module Status Word Format starting on page 38 for a full
description of the response bits.
Bit 9 Bit 8 Description
0 0 Not setting Null position for the channel
0 1
The channel is searching for the null point. Movement must occur to
increase the voltage on the B channel to reach the null point.
1 0
The channel is searching for the null point. Movement must occur to
increase the voltage on the A channel to reach the null point.
1 1 The channel is at its null point.
Word Configuration Data Range
0 Command Word 16#9008
1 Null Value MSW
32 bit sign-magnitude position value.
Valid range of ±2,147,483,647.
2 Null Value LSW
3 Not Used 16#0000
4 Not Used 16#0000
5 Not Used 16#0000
6 Not Used 16#0000
7 Not Used 16#0000
8 Not Used 16#0000
9 Not Used 16#0000