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
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.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:
|
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).
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).
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. |
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16#21 33 | The Output Status input transitioned from ON (1) to OFF (0) while the instruction was executing. |
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16#5000 20480 | Feedback 1 and Feedback 2 turned OFF (0) unexpectedly. |
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16#5001 20481 | Feedback 1 turned OFF (0) unexpectedly. |
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16#5002 20482 | Feedback 2 turned OFF (0) unexpectedly. |
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16#5003 20483 | Feedback 1 and Feedback 2 turned ON (1) unexpectedly. |
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16#5004 20484 | Feedback 1 turned ON (1) unexpectedly. |
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16#5005 20485 | Feedback 2 turned ON (1) unexpectedly. |
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16#5006 20486 | Feedback 1 and Feedback 2 did not turn ON (1) within the configured Feedback Reaction Time. |
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16#5007 20487 | Feedback 1 did not turn ON (1) within the configured Feedback Reaction Time. |
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16#5008 20488 | Feedback 2 did not turn ON (1) within the configured Feedback Reaction Time. |
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16#5009 20489 | Feedback 1 and Feedback 2 did not turn OFF (0) within the configured Feedback Reaction Time. |
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16#500A 20490 | Feedback 1 did not turn OFF (0) within the configured Feedback Reaction Time. |
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16#500B 20491 | Feedback 2 did not turn OFF (0) within the configured Feedback Reaction Time. |
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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). |
Provide Feedback