ProSoft Technology MVI56E-MCMR - Manual (Page 156)

Reference MVI56E-MCMR ♦ ControlLogix Platform
User Manual Modbus Communication Module with Reduced Data Block
Page 156 of 225 ProSoft Technology, Inc.
May 13, 2014
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.