Reference
MVI56E-MCMR ♦ ControlLogix Platform
User Manual
Modbus Communication Module with Reduced Data Block
Page 154 of 223
ProSoft Technology, Inc.
Event Command Blocks (9901, 9911)
The
Event Command
special function is applicable only when the module's port
is configured as a Modbus Master.
Event Commands
are best used to send
commands based on special process conditions, such as emergency shutdowns
or device-specific resets. Whenever an
Event Command
data block is received
by the module, it will insert the requested command into the beginning of the
Command Queue, so that the special command is sent before the next regular
polling command.
Sending a message (MSG instruction) containing
Event Command Block
Identification Code
9901
for Port 1 or
9911
for Port 2 will cause the module to
issue one user-constructed command. All the data required for one Modbus
command must be included in the MSG instruction using the
Event Command
Block ID Code
.
If you use the provided sample ladder logic or Add-On Instruction (AOI), the
Modbus Command parameter data required for this special function block will be
placed in the controller tag array,
MCMR.CONTROL.E
VENT
C
MD
P1[0]
. for Port 1
or
MCMR.CONTROL.E
VENT
C
MD
P2[0]
for Port 2. Once the command
parameters have been properly loaded into this array element, the
Event
Command
special function can be executed by setting a value of one (1) into the
controller tag,
MCMR.CONTROL.E
VENT
T
RIGGER
P1
for Port 1 or
MCMR.CONTROL.E
VENT
T
RIGGER
P2
for Port 2.
You will notice that
MCMR.CONTROL.E
VENT
C
MD
P1[
X
]
and
MCMR.CONTROL.E
VENT
C
MD
P2[
X
]
are actually 100-element arrays, capable of
holding up to 100 pre-configured command parameter sets. However, at this
time, only the first element of each array,
MCMR.CONTROL.E
VENT
C
MD
P1[0]
or
MCMR.CONTROL.E
VENT
C
MD
P2[0]
is used in the MSG instructions of the
sample ladder logic or AOI. If you wish to use the other 99 elements of this array
to hold potential
Event Commands
that you might want to execute, you will need
to create additional logic to use them. You could:
1
Create logic to COPY the parameter data from any array element, 1-99, into
element 0 before triggering the
Event Command
MSG instruction.
2
Create logic that duplicates the sample MSG instruction, modify it for a
specific array element, create a unique trigger tag for this logic, and use
these to send the specific pre-configured
Event Command
contained in that
array element.
The following table lists the parameters required for a user-constructed
Event
Command
and shows the order in which the parameters will be passed by the
MSG instruction. You will notice, these are the same parameters and are in the
same order as in any normal polling command you create in the configuration file
for the Master port.