Rockwell Automation 1746-NI16V SLC 500 Analog Input Modules User Manual - Manual (Page 55)

Publication 1746-UM001A-US-P
Channel Configuration, Data, and Status 5-7
Class 1 Handshaking (Bit 2)
In Class 1, the module provides handshaking to simplify
configuration. This handshaking feature is the fastest way to configure
the module’s 16 channels. To transmit a channel’s configuration, bit 2
should be set to 1. When the module has completed this instruction, a
1 is placed in bit 6 of the status word. To reset bit 6 of the status word
to 0, reset bit 2 in the configuration word to 0. After channels 0
through 7 are configured, then channels 8 through 15 can be
configured. An application example for Class 1, using bits 2 and 6 to
perform configuration handshaking for all 16 channels, can be found
on page 7-1. The handshaking between bits 2 and 6 is not needed in
Class 3 since all 32 words of data and status can be sent and received
at once.
Class 1 Data or Status Configuration (Bits 1 and 0)
Bits 1 and 0 are only used in Class 1 mode. If these bits are set while
in Class 3 mode, a configuration error is set in the status word (bits 15,
14 and 13 set to 0, 1, and 1). The use of these bits is not necessary in
Class 3 because Class 3 allows for data transfer of a 32-word block. In
Class 1 mode, data transfer is limited to 8-word blocks. The 1746-NI16
has the ability to communicate 16 words of data and 16 words of
status information. Therefore, the user can choose which block of 8
words is needed via bits 1 and 0 in the configuration word. This is
done in the following manner:
Set Bit 0 to: to select channels: Set Bit 1 to: to select:
0 0 through 7 0 data
1 8 through 15 1 status information
NOTE
For a description of data reporting in the status
word, see “Input Word Bit Definitions” on page 5-20.