ProSoft Technology MVI56-LTQ - Manual (Page 33)

MVI56-LTQ ♦ ControlLogix Platform Ladder Logic
Limitorque Valve Actuator Master Communication Module User Manual
ProSoft Technology, Inc. Page 33 of 98
August 30, 2010
Information in this structure contains the status and monitor information for each
valve in the system. This information should be considered by the user control
logic to determine the status and control required for each valve to be utilized in a
system. It is important to note that slave 1 has an array index of 0. This offset
applies to all valves (slave 150 has an index of 149).
The next data set received from the module is the DoneBits array. Each slave in
the system is associated with a bit in the array. Each element contains the done
bit status for 16 slave units ([0]=slaves 1 to 16, [1]=slaves 17 to 32, and so on). It
is important to use these bits to clear the commands issued using the next data
sets. Commands issued to the module to generate messages on the Limitorque
Valve Network are issued in a one-shot operation. After an event command is
issued to the slave, the done bit for the slave is set. This bit is held high for one
scan of the module and then is reset in the data transfer block. Ladder logic
should clear the commands for each slave using the status of the done bit.
The last set of data in the module object contains the control information for the
valves. This data is to be controlled by the ladder logic. An array is defined for
each of the command instructions available through the module. Each bit in the
array is associated with a slave. Bit 0 in word 0 corresponds to slave 1, and Bit 0
in word 1 corresponds to slave 17. An array of LTQCont objects is defined for the
contactor engage/disengage commands. The following table describes the
structure of this object.
Name Data Type Description
Engage INT[10] Engage Command
Disengate INT[10] Disengage Command
In order to execute one of the commands, set the bit for the selected slave in the
array. For example, to open slave-3 valve, set bit 2 in word 0 of the Open array.
For the analog control commands, set the value for the analog first (AnalogPos[
]), then set the analog control array bit (AnalogCmd[ ]). The analog position
requires two commands. The first command issued by the module sets the
position in the valve. The second command instructs the valve to seek the new
position.