58 310531
Theory of Operation
Fault Handling
Fault Strobe
Fault Code Data
>
>1 msec
Fig. 36
Fault code data is valid for a minimum of 1 msec
before FAULT STROBE goes HIGH. Fault code data
remains valid, and the FAULT STROBE remains
HIGH, until a FAULT ACKNOWLEDGE is received
from the robotic controller, or the fault is cleared using
the pendant.
Fault codes are reported using the FAULT STROBE
signal and the data bus. Fault codes can be either:
alarms, which cause the PrecisionFlo module to
shut down
warnings, which allow the PrecisionFlo module to
keep operating
The robot can read a fault code immediately or at the
end of the cycle. If an alarm occurs after a warning,
the alarm will be displayed instead of the warning. At
the end of the dispense cycle the data bus is used for
volume reporting, if requested by the robotic controller.
Once volume reporting has been completed, the last
previous fault code is placed on the data bus.
Fault codes are reported to the robotic controller in
conjunction with the FAULT STROBE signal. The fault
code value is obtained by adding the values assigned
to the fault code bits that are HIGH.
The values of the fault bits are:
Bit
Fault Bit Value
0
1
1
2
2
4
3
8
4
16
For example, if bits 2 and 3 are HIGH, the fault code
value is equal to 4 + 8, or 12, and a Volume Fault is
indicated.
Typical Fault Handling Procedure
1.
A problem occurs in the PrecisionFlo module.
2.
The PrecisionFlo module analyzes the problem
indication and determines if the fault is an alarm or
a warning.
3.
If the fault is an alarm:
a.
The PrecisionFlo module disables the MCR,
which sets the DISPENSER READY signal
LOW and shuts down the module.
b.
Then the PrecisionFlo module places the fault
code on the data bus and sets the FAULT
STROBE signal HIGH.
The robot can detect the fault strobe signal and
read the fault data immediately or at the end of the
cycle (see steps 4 and 5).
NOTE: A fault condition causing an alarm must be
corrected, and the PrecisionFlo module must be
placed back in an operating mode using the control
pendant, before dispensing can resume.
If the fault is a warning, normal operation contin-
ues to the end of the cycle.
4.
On completion of the cycle, if volume information
is requested, the PrecisionFlo module uses the
data bus to transfer the volume data. (See Fig-
ure 37, Volume Reporting on page 59.)
5.
Once the cycle is completed and any volume
information has been transferred, the PrecisionFlo
module places the last occurring warning code on
the data bus. The robot has the option of reading
the warning code or not, and can initiate another
cycle.
Refer to the Troubleshooting and Fault Recovery
section page 48 for fault code causes, descriptions,
and solutions for the various faults.