Rockwell Automation 1771-QC , D17716.5.25 SER/B SERVO POS - Manual (Page 94)

Formatting and Interpreting Data Blocks
Chapter 7
7Ć12
When you detect that this bit is on, you may want to turn on bit 11 of axis
control word 2 in the command block to display diagnostic status in the
3rd and 4th status words for the axis.
Bits 12, 11, 10 Block ID
These bits are the block ID of the moveset block currently being executed,
unless the diagnostic valid bit (bit 6) is on. When the programming error
bit is on, bits 10 thru 12 indicate the block in which the error was
detected:
ID
(Bits 12, 11, 10) Block
000 Parameter
001 Axis 1 Odd Moveset
010 Axis 2 Odd Moveset
011 Axis 3 Odd Moveset
100 Axis 1 Even Moveset
101 Axis 2 Even Moveset
110 Axis 3 Even Moveset
111 Command
Bit 13 Axis Fault
The 1771-M3 controller turns on this bit when communication between it
and the 1771-ES expander is lost.
Bit 14 Following Error Valid
This bit is on if the next two status block words for this axis contain axis
following error.
Bit 15 Position Valid
This bit is on if the next two status block words for this axis contain axis
position.
If the axis position value exceeds the maximum allowable value
(999.9999 in or 19999.999 mm), the servo positioning assembly turns off
both the position valid and following error valid bits (bits 15 and 14), and
sets the position value in the status block at the maximum value.