Rockwell Automation 1794-VHSC 1794 FLEX I/O Very High Speed Counter Module User Manual - Manual (Page 47)

Rockwell Automation Publication 1794-UM010D-EN-E - July 2013 39
Communicate With Your Module
Word 8 12 (14) Test/fail bit (TF) – If the flexbus power or terminal base power is
applied and the module fails during hardware tests, a fatal error occurs.
The TF bit is asserted and the red module indicator turns on. An error
code will be set in the module/channel status word which can be read
using an instruction. The TF bit is also asserted if the upper byte of the
counter control word is not zero.
The upper byte of the counter control word (output word 0) is reserved
for special mode, Enhancing Frequency/Resolution. To use this mode,
set bit 11, and set a value in output word 2 and/or word 3. When the
upper byte of word 0 is not zero, the red module status indicator will
flash and the TF bit is asserted to indicate the module has entered a
test-mode state. Clearing the upper byte of output word 0 restores the
module to an operation state, clears the TF bit and returns the indicator
to green.
Change significant digits of frequency display based on word 14 for
channel 0 and word 15 for channel 1 (-2 moves decimal point left 2
places dividing the frequency value by 100; +1 moves the decimal point
1 place, multiplying by 10, and so on).
This allows frequency values to fit in a single word.
Note: To use Frequency/Resolution Enhancement feature provides
appropriate configuration for each frequency mode (Mode 5,6,7).
Firmware revision D changed decimal point placement to absolute
positioning. Revision D firmware also checks for placement to be in the
range of -4…+2. A value outside the range moves the decimal point to
the zero position. Moving the decimal point to the left allows high
frequencies, (commonly present in rate measurement) to fit within a
single word. Moving the decimal point to the right allows low
frequencies (commonly present in period and continuous rate modes) to
have resolution displayed to 0.1 Hz and 0.01 Hz. Do not use scalars of Z/
128, Z/64, Z/32 and Z/16 when using this test mode.
13 (15) Not ready status bit (NR) – Whenever 24V DC power is applied to the
module, the hardware must be initialized. The NR bit will be asserted
and the red module indicator will flash. If the red indicator continues
flashing, and the green indicator momentarily turns on, the 24V DC
power is below the module minimum.
14 (16) Field power fault bit (FP) – If the 24V DC module power drops, the FP
bit is asserted, the green module indicator flashes, the module outputs
turn off, and the module enters an idle state reporting status as it waits
for power to be restored.
Note: this bit does not indicate status of either output customer
power supply.
15 (17) Programming error bit (PE) – This bit is asserted if incomplete,
incorrect or conflicting set of configuration parameters are sent to the
module. The green module status indicator will flash and an error code
will be placed in bits 11:0 of the module/channel status word. The
module will not enter a normal operating state. Bit definitions are
shown in Table
Input Status Word Bits on page 32 .
Bit/Word Definitions
Input Word Bit Definition