43
CMA USER MANUAL
E-VLMB-TT005-E April 2019 www.eaton.com
CMA User Manual
Table 39 . 7 .2 .4 Algorithm select enumerations
Algorithm
Debug output
1
Flow
2
PWM
3
Position
4
Pressure
5
Pressure Limit
6
Off
7.3 Pilot valve replacement
As described in the VSM Valve Replacement Configuration
section, the CMA valve has built in capability to either
automatically replace work section pilots and inlet section
pilots, or replace valves based on received user commands.
For the detailed procedure on how to mechanically remove
and install a new pilot, refer to the Service Guide. Make
sure that when a pilot valve is replaced, that the valve
power is disconnected. Once the pilot has been replaced,
if the system is configured to be in Automatic mode, the
system controller will detect the new pilot and start the
replacement procedure. An overview of the replacement
procedure is given below.
7.3.1 Work section pilot valve replacement
Once a new pilot valve has been detected, if the VSM is
in automatic mode, it will restore all of the application and
mechanical data from the old pilot on to the new one. If
the VSM is configured to be in manual replacement mode,
then it will issue a periodic Valve Pending message and wait
for a user command. The user can select whether to copy
the mechanical parameters, the non-mechanical application
parameters, both, or none. If only a pilot valve is replaced,
then all of the parameters should be copied from the old
valve to the new one. This will maintain the flow calibration
that is performed in the plant. If the pilot valve AND the
main stage work section have been replaced, then only
the non-mechanical parameters should be copied. This will
maintain the flow calibrations that come with the new pilot/
main stage section. Refer to the Application Developers
Guide for a detailed description of the valve replacement
communication protocol. After the parameters are copied,
the valve will issue two messages upon successful
replacement. The first message will be a request for the
replaced pilot valve to be air bled. This is necessary to
purge the air between the pilot and the main stage spool.
The air bleed message protocol is described in detail in the
Application Developers Guide.
Ensure that during an air bleed the service is in a no
load holding state, as air bleed will cycle the spools
from end stop to end stop in an open loop manner .
Once air bleed has completed, the valve will then issue a
train pending message. The train pending message is for
the new pilot to learn the characteristics of itself as well as
the characteristics of the main stage. This is meant to be a
self-calibration procedure and no action is required by the
user other than issuing the train request. As with the air
bleed procedure, the message protocol for training can be
found in the Application Developers Guide. During training,
the valve will cycle the main stage spool in a couple of
different formats to establish its new mechanical limits and
to tune the position controller.
Make sure the machine is at rest so that no loads will
be released during the training .
otee:
N
If you are using Pro-FX Configure, the airbleed and
train procedure can easily be commanded from the
tools menu.
7.3.2 Inlet section replacement
As with the pilot valves from the work sections, if an inlet
controller is determined to have been replaced, the VSM
can copy all of its application data to the new inlet controller.
Replacing the inlet pilot valve (CV) is treated as a valve
replacement when determining whether to use Automatic
or Manual mode. In Manual mode, the user can again
select whether to copy the mechanical parameters, the
non-mechanical parameters, both, or none. For the current
version of software, the inlet does not have any mechanical
calibration parameters that are determined in the plant; they
are all determined during the training procedure. Thus, there
is no danger in copying all of the parameters on the inlet
pilot, regardless of whether the pilot or the pilot and main
stage have been replaced. Upon successful completion, the
inlet controller will then need to be ‘trained’. As with the
work section pilots, the inlet training is a method for the
pilot to learn its own physical characteristics. In the inlet,
airbleeding is included as the first step of training. It can
also be commanded using the same protocol as for the Pilot
Valves. Note that as a part of training, the inlet will sweep
through nearly its entire pressure range (as specified by the
Minimum and
Maximum Inlet Pressures). If there is some external
mechanical pressure limitation in the system (i.e. a relief
valve or a pressure compensator) that prevents the system
from reaching close to its specified maximum pressure,
then the valve can get stuck in Training.
