Main Valve Control (MVC)

This instruction applies to the Compact GuardLogix 5370, GuardLogix 5570, Compact GuardLogix 5380, and GuardLogix 5580 controllers.
The Main Valve Control (MVC) instruction is used to control and monitor the main clutch or brake valve. This instruction supports valves with various reaction times and positive or negative feedback signals. Single-channel valves are supported by combining Output 1 and Output 2 to control the valve and combining Feedback 1 and Feedback 2 for monitoring.
Available Languages
Ladder Diagram
RSL5K_MVC Ladder Diagram_v31
Function Block
This instruction is not available in function block.
Structured Text
This instruction is not available in structured text.
Operands
IMPORTANT:
Unexpected operation may occur if:
  • Output tag operands are overwritten.
  • Members of a structure operand are overwritten.
  • Structure operands are shared by multiple instructions.
WARNING:
If changing instruction operands while in Run mode, accept the pending edits and cycle the controller mode from Program to Run for the changes to take effect.
The following table provides the operand used to configure the instruction. These operands cannot be changed at runtime.
Operand
Data Type
Format
Description
MVC
MAIN_VALVE_CONTROL
tag
MVC structure
Feedback Type
BOOL
list item
This operand defines the feedback OFF and ON states for positive and negative feedback signals.
Positive (1)
OFF (0): Feedbacks OFF / Outputs OFF
ON (1): Feedbacks ON / Outputs ON
Negative (0)
OFF (0): Feedbacks ON / Outputs OFF
ON (1): Feedbacks OFF / Outputs ON
Feedback Reaction Time
DINT
immediate
This operand specifies the amount of time that the instruction waits for Feedback 1 and Feedback 2 inputs to reflect the state of Output 1 and Output 2 as defined by the Feedback Type operand.
The valid range is 5 to 1000 ms.
The following table explains the instruction inputs. The inputs can be field device signals from input devices or be derived from the user logic.
Operand
Data Type
Format
Description
Actuate
BOOL
tag
This input energizes or de-energizes Output 1 and Output 2.
OFF (0) - > ON (1): Output 1 and Output 2 are energized if no faults exist.
ON (1) - > OFF (0) Output 1 and Output 2 are de-energized.
Feedback 1
BOOL
tag
These inputs are constantly monitored to make sure that they reflect the state of Output 1 and Output 2. When Output 1 and Output 2 transition, these inputs must react within the Feedback Reaction Time.
Feedback 2
BOOL
tag
Input Status
BOOL
tag
immediate
If instruction inputs are from a safety I/O module, this value is the status from the I/O module or modules (Connection Status or Combined Status). If instruction inputs are derived from internal logic, it is the application programmer’s responsibility to determine the conditions.
ON (1): The inputs to this instruction are valid.
OFF (0): The inputs to this instruction are invalid.
Output Status
BOOL
tag
immediate
This input indicates the output status of the I/O module or modules used by this instruction.
ON (1): The output module is operating properly.
OFF (0): The output module is faulted. Instruction outputs are set their de-energized (safe) state.
Reset
1
BOOL
tag
This input clears the instruction faults provided the fault condition is not present.
ON (1): The Fault Present and Fault Code outputs are reset.
1
 ISO 13849-1 stipulates instruction reset functions must occur on falling edge signals. To comply with ISO 13849-1 requirements, add this logic immediately before this instruction. Rename the ‘Reset_Signal’ tag in the example shown below to the reset signal tag name. Then use the OSF instruction Output Bit tag as the instruction’s reset source.
RSL5K_MMVC Reset-Signal Example_v31
The following table explains the instruction outputs. The outputs can be field device signals or be derived from user logic.
Operand
Data Type
Description
Output 1 (01)
BOOL
A redundant pair, these outputs are used to control a press clutch or brake valve. The outputs are de-energized when the following occurs:
  • A feedback fault occurs.
  • Input Status or Output Status inputs turn OFf
  • The normal operation of the instruction causes Output 1 and Output 2 to be de-energized as described in the timing diagram.
Output 2 (02)
BOOL
Fault Present (FP)
BOOL
ON (1): A fault is present in the instruction.
OFF (0): The instruction is operating normally.
Fault Code
DINT
This output indicates the type of fault that occurred. See the Fault Codes section below for the list of fault codes.
This operand is not safety-related
Diagnostic Code
DINT
This output indicates the diagnostic status of the instruction. See the Diagnostic Codes section below for a list of diagnostic codes.
This operand is not safety-related.
IMPORTANT:
Do not write to any instruction output tag under any circumstances.
Affects Math Status Flags
No
Major/Minor Faults
None specific to this instruction. See Index Through Arrays for array-indexing faults.
Execution
Condition/State
Action Taken
Prescan
Same as Rung-condition-in is false.
Rung-condition-in is false
The .O1, .O2, and .FP outputs are cleared to false.
The Diagnostic Code and Fault Code outputs are set to 0.
Rung-condition-in is true
The instruction executes.
Postscan
Same as Rung-condition-in is false.
Operation
Normal
This timing diagram shows normal operation of this instruction to control a press clutch or brake valve with Feedback Type = Positive. Outputs 1 and 2 are energized when the Actuate input transitions from OFF (0) to ON (1) at (A). Both feedback inputs react before the Feedback Reaction Time expires, so the outputs remain energized in a steady state at (B). Outputs 1 and 2 are de-energized at (C) when the Actuate input transitions from ON (1) to OFF (0). Both of the feedback inputs react before the Feedback Reaction Time expires so the outputs remain de-energized in steady state at (D).
MVC Normal Operation diagram
Feedback Fault
The following diagram is an example of how a feedback fault can occur when either of the Feedback inputs fail to reflect the state of Outputs 1 and correctly with Feedback Type = Positive. Outputs 1 and 2 are energized at (A), but at (B), Feedback 2 has not transitioned from OFF (0) to ON (1) before the Feedback Reaction Time has expired, which generates a Feedback fault. The fault cannot be cleared at (C) because the Feedbacks 1 and 2 do not yet reflect the state of Outputs 1 and 2. The fault is cleared when an OFF (0) to ON (1) transition is detected on the Reset input and both Feedback inputs are OFF (0), correctly reflecting the state of Outputs 1 and 2 at (D).
MVC Feedback Fault
False Rung State Behavior
When the instruction is executed on a false rung, all instruction outputs are de-energized.
Fault Codes and Corrective Actions
The fault codes are listed in hexadecimal format followed by decimal format.
Fault Code
Description
Corrective Action
0
No fault.
None
16#20
32
The Input Status input transitioned from ON (1) to OFF (0) while the instruction was executing.
  • Check the I/O module connection.
  • Reset the fault.
16#21
33
The Output Status input transitioned from ON (1) to OFF (0) while the instruction was executing.
  • Check the I/O module connection.
  • Reset the fault.
16#5000
20480
Feedback 1 and Feedback 2 turned OFF (0) unexpectedly.
  • Check the feedback signal.
  • Reset the fault.
16#5001
20481
Feedback 1 turned OFF (0) unexpectedly.
  • Check the feedback 1 signal.
  • Reset the fault.
16#5002
20482
Feedback 2 turned OFF (0) unexpectedly.
  • Check the feedback 2 signal.
  • Reset the fault.
16#5003
20483
Feedback 1 and Feedback 2 turned ON (1) unexpectedly.
  • Check the feedback signals.
  • Reset the fault.
16#5004
20484
Feedback 1 turned ON (1) unexpectedly.
  • Check the feedback 1 signal.
  • Reset the fault.
16#5005
20485
Feedback 2 turned ON (1) unexpectedly.
  • Check the feedback 2 signal.
  • Reset the fault.
16#5006
20486
Feedback 1 and Feedback 2 did not turn ON (1) within the configured Feedback Reaction Time.
  • Check the feedback signal.
  • Adjust the Feedback Reaction Time, if necessary
  • Reset the fault.
16#5007
20487
Feedback 1 did not turn ON (1) within the configured Feedback Reaction Time.
  • Check the feedback 1 signal.
  • Adjust the Feedback Reaction Time, if necessary
  • Reset the fault.
16#5008
20488
Feedback 2 did not turn ON (1) within the configured Feedback Reaction Time.
  • Check the feedback 2 signal
  • Adjust the Feedback Reaction Time, if necessary
  • Reset the fault.
16#5009
20489
Feedback 1 and Feedback 2 did not turn OFF (0) within the configured Feedback Reaction Time.
  • Check the feedback signal
  • Adjust the Feedback Reaction Time, if necessary
  • Reset the fault.
16#500A
20490
Feedback 1 did not turn OFF (0) within the configured Feedback Reaction Time.
  • Check the feedback 1 signal
  • Adjust the Feedback Reaction Time, if necessary
  • Reset the fault.
16#500B
20491
Feedback 2 did not turn OFF (0) within the configured Feedback Reaction Time.
  • Check the feedback 2 signal
  • Adjust the Feedback Reaction Time, if necessary
  • Reset the fault.
Diagnostic Codes and Corrective Actions
The diagnostic codes are listed in hexadecimal format followed by decimal format.
Diagnostic Code
Description
Corrective Action
0
No fault.
None
16#20
32
The Input Status was OFF (0) when the instruction started.
Check the I/O module connection.
16#21
33
The Output Status input transitioned from ON (1) to OFF (0) while the instruction was executing.
Check the I/O module connection.
16#5000
20480
The Actuate input is held ON (1).
Set the Actuate input to OFF (0).
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