# Menu 14 − User PID Controller

Mode: RFC‑A

PID controllers

Two general purpose PID controllers are provided as shown in the diagram below. Both operate in the same way except that PID controller 2 does not include a pre-sleep boost reference or alternative feedback and error selection. In the following sections a description is given for PID controller 1. The descriptions also apply to PID controller 2 except where stated. The sample rate for the PID controllers is always 4ms.

Parameter | 14.001 PID1 Output
--- | ---
Short description | Displays the output for PID1
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 2
Coding | RO, ND, NC, PT

Controller

The controller section for the PID controllers is shown in the introduction. The structure of PID controller 1 shown in the introduction is when PID1 Mode Selector (14.059) = 0, PID1 Feedback Output Scaling (14.058) = 1.000, and PID1 Feedback Square Root Enable 2 (14.062) = 0. The additional features provided by these parameters are not available for PID controller 2, and so this controller always has the structure shown. If the combined enable is inactive then all internal states are held at zero and the destination parameter will be defined by PID1 Feed-forwards Reference (14.019) alone. If the enable is active the PID controller is active even if the destination is not routed to a valid parameter or to 0.000. It should be noted that if either of the enable sources is routed to 0.000 or to a non-valid parameter the source value is taken as 1, therefore with default settings, PID1 Enable Source 1 (14.009) = 0.000 and PID1 Enable Source 2 (14.027) = 0.000, the PID controller can be enabled by simply setting PID1 Enable (14.008).

PID1 Error (14.022) is the difference between the reference and feedback produced by the reference and feedback systems described in the previous sections. The PID controller output is defined as follows:

PID1 Output (14.001) = PID1 Error (14.022) x [Kp + Ki/s + sKd/(0.064s + 1)]

Kp = PID1 Proportional Gain (14.010)

Ki = PID1 Integral Gain (14.011)

Kd = PID1 Differential Gain (14.012)

Therefore:

> 1. If PID1 Error (14.022) = 100.00% the proportional term gives a value of 100.00% if PID1 Proportional Gain (14.010) = 1.000.

> 2. If PID1 Error (14.022) = 100.00% the integral term gives a value that increases linearly by 100.00% per second if PID1 Integral Gain (14.011) = 1.000.

> 3. If PID1 Error (14.022) increases linearly by 100.00% per second the differential term gives a value of 100.00% if PID1 Differential Gain (14.012) = 1.000. (A filter with a time constant of 64ms is provided on the differential gain to reduce the noise produced by this term.)

The output may be limited to a range that is less than the maximum range of PID1 Output (14.001) using PID1 Output Upper Limit (14.013) and PID1 Output Lower Limit (14.014). If PID1 Output Lower Limit (14.014) > PID1 Output Upper Limit (14.013) then the output is held at the value defined by PID1 Output Upper Limit (14.013). If PID1 Symmetrical Limit Enable (14.018) = 1 then the lower limit = -(PID1 Output Upper Limit (14.013)). If the output reaches either of these limits the integral term accumulator is frozen until the output moves away from the limit to prevent integral wind-up. The integral hold function can also be enabled by the user by setting PID1 Integral Hold (14.017) = 1.

PID1 Output Scaling (14.015) can be used to scale the output, which is limited to a range from -100.00% to 100.00% after this function. The output is then added to PID1 Feed-forwards Reference (14.019) and is again limited to the range from -100.00% to 100.00% before being routed to the destination defined by PID1 Destination (14.016).

Parameter | 14.002 PID1 Feed-forwards Reference Source
--- | ---
Short description | Defines the input source for the feed-forwards reference source for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, PT, BU

See PID1 Output (14.001).

Parameter | 14.003 PID1 Reference Source
--- | ---
Short description | Defines the input source for the reference for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, PT, BU

The reference section for the PID controllers is shown in the introduction. The pre-sleep boost control is only included in PID controller 1. The reference sections are always active even if the PID controller itself is disabled or the reference sources are not routed to valid parameters. If a reference source is not a valid parameter or is 0.000 then the value is taken as zero.

The reference is the sum of the reference source, the PID1 Digital Reference (14.025) and the PID1 Pre-sleep Boost Level (14.028) when it is active. The result is multiplied by PID1 Reference Scaling (14.023) and then limited to +/-100.00%. The reference can then be inverted if required (PID1 Reference Invert (14.005) = 1) and then a slew rate limit is applied with PID1 Reference Slew Rate (14.007). This limits the maximum rate of change so that a change from 0.00 to 100.00% takes the time given in PID1 Reference Slew Rate (14.007).

Sleep mode is used to stop the motor if the frequency or speed reference falls below a specified level so that the system does not run inefficiently at low speeds (see Sleep / Wake Threshold (06.053)). If the frequency or speed reference is controlled by PID controller 1 then the PID controller feedback will fall when sleep mode becomes active because the motor has stopped. The PID controller output will rise again above the sleep/wake threshold and the motor will restart. To minimise the number of transitions into and out of sleep mode the sleep condition can be delayed and an increased reference applied during this period by setting PID1 Pre-sleep Boost Level (14.028) to a non-zero value. When Sleep Required (06.056) = 1 the PID1 Pre-sleep Boost Level (14.028) is added to the reference until PID1 Error (14.022) is reduced below zero or until this additional reference has been applied for PID1 Maximum Boost Time (14.029). This system is only intended for applications where PID controller 1 alone is used to control the motor frequency or speed via the Menu 1 reference system and the motor rotates in the positive direction under normal conditions. When the PID output first falls below the Sleep / Wake Threshold (06.053) it is possible for PID1 Error (14.022) to be negative because of a positive value remaining in the integral accumulator. To allow the error to become positive so that the boost period is not terminated immediately, the PID1 Pre-sleep Boost Level (14.028) is applied for a minimum of 100ms before the end of the boost period can be terminated because PID1 Error (14.022) is greater than or equal to zero.

Parameter | 14.004 PID1 Feedback Source
--- | ---
Short description | Defines the input source for the feedback for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, PT, BU

Feedback

The feedback section for the PID controllers is shown in the introduction. The feedback sections are always active even if the PID controller itself is disabled or the feedback sources are not routed to valid parameters. If a reference source is not a valid parameter or is 0.000 then the value is taken as zero.

The feedback is the sum of the feedback source and the PID1 Digital Feedback (14.026). The result is multiplied by PID1 Feedback Scaling (14.024) and then limited to +/-100.00%. A square root function can be applied (PID1 Feedback Square Root Enable 1 (14.060) = 1) and the feedback can then be inverted if required (PID1 Feedback Invert (14.006) = 1). The square root function is defined as follows.

Square root function output = Sign(Input) x 100.00% x √(|Input| / 100.00%)

where Sign(Input) = 1 if Input ≥ 0 or -1 otherwise

The square root function is useful in applications where the PID controller is operating with air flow as its reference and feedback and the motor is controlling a fan. It is easier to use a pressure transducer than a flow transducer, and so the feedback from the transducer needs to be converted from pressure to flow. As flow = Constant x √Pressure the square root function can be used in the conversion.

Parameter | 14.005 PID1 Reference Invert
--- | ---
Short description | Set to 1 to invert PID1 reference
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Reference Source (14.003).

Parameter | 14.006 PID1 Feedback Invert
--- | ---
Short description | Set to 1 to invert the PID1 feedback
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Feedback Source (14.004).

Parameter | 14.007 PID1 Reference Slew Rate
--- | ---
Short description | Defines the rate in change of output for PID1
Mode | RFC‑A
Minimum | 0.0 | Maximum | 3200.0
Default | 0.0 | Units | s
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 1
Coding | RW

See PID1 Reference Source (14.003).

Parameter | 14.008 PID1 Enable
--- | ---
Short description | Enables the use of PID1
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Output (14.001).

Parameter | 14.009 PID1 Enable Source 1
--- | ---
Short description | Defines the input source for enabling PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, PT, BU

See PID1 Output (14.001).

Parameter | 14.010 PID1 Proportional Gain
--- | ---
Short description | Defines the Kp gain used for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 1.000 | Units |
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Output (14.001).

Parameter | 14.011 PID1 Integral Gain
--- | ---
Short description | Defines the Ki gain used for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 0.500 | Units |
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Output (14.001).

Parameter | 14.012 PID1 Differential Gain
--- | ---
Short description | Defines the Kd gain used for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Output (14.001).

Parameter | 14.013 PID1 Output Upper Limit
--- | ---
Short description | Defines the maximum value of the output for PID1
Mode | RFC‑A
Minimum | 0.00 | Maximum | 100.00
Default | 100.00 | Units | %
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 2
Coding | RW

See PID1 Output (14.001).

Parameter | 14.014 PID1 Output Lower Limit
--- | ---
Short description | Defines the minimum value of the output for PID1
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default | -100.00 | Units | %
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 2
Coding | RW

See PID1 Output (14.001).

Parameter | 14.015 PID1 Output Scaling
--- | ---
Short description | Defines the scaling factor of the output for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 1.000 | Units |
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Output (14.001).

Parameter | 14.016 PID1 Destination
--- | ---
Short description | Defines the output parameter for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, DE, PT, BU

See PID1 Output (14.001).

Parameter | 14.017 PID1 Integral Hold
--- | ---
Short description | Enables the integral hold function for PID1
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit Volatile | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Output (14.001).

Parameter | 14.018 PID1 Symmetrical Limit Enable
--- | ---
Short description | Enables the symmetrical limit for PID1
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Output (14.001).

Parameter | 14.019 PID1 Feed-forwards Reference
--- | ---
Short description | Displays the value of the feed-forwards reference for PID1
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 2
Coding | RO, ND, NC, PT

See PID1 Output (14.001).

Parameter | 14.020 PID1 Reference
--- | ---
Short description | Displays the value of the reference for PID1
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 2
Coding | RO, ND, NC, PT

See PID1 Reference Source (14.003).

Parameter | 14.021 PID1 Feedback
--- | ---
Short description | Displays the value of the feedback for PID1
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 2
Coding | RO, ND, NC, PT

See PID1 Feedback Source (14.004).

Parameter | 14.022 PID1 Error
--- | ---
Short description | Displays the value of the error for PID1
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 2
Coding | RO, ND, NC, PT

See PID1 Output (14.001).

Parameter | 14.023 PID1 Reference Scaling
--- | ---
Short description | Defines the scaling factor for the reference for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 1.000 | Units |
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Reference Source (14.003).

Parameter | 14.024 PID1 Feedback Scaling
--- | ---
Short description | Defines the scaling factor of the feedback for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 1.000 | Units |
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Feedback Source (14.004).

Parameter | 14.025 PID1 Digital Reference
--- | ---
Short description | Defines the value of the digital reference for PID1
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default | 0.00 | Units | %
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 2
Coding | RW

See PID1 Reference Source (14.003).

Parameter | 14.026 PID1 Digital Feedback
--- | ---
Short description | Defines the value of the digital feedback for PID1
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default | 0.00 | Units | %
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 2
Coding | RW

See PID1 Feedback Source (14.004).

Parameter | 14.027 PID1 Enable Source 2
--- | ---
Short description | Defines the input source for enabling PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, PT, BU

See PID1 Output (14.001).

Parameter | 14.028 PID1 Pre-sleep Boost Level
--- | ---
Short description | Defines the level of the pre-sleep boost function
Mode | RFC‑A
Minimum | 0.00 | Maximum | 100.00
Default | 0.00 | Units | %
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 2
Coding | RW

See PID1 Reference Source (14.003).

Parameter | 14.029 PID1 Maximum Boost Time
--- | ---
Short description | Defines the maximum time that the boost level can be used
Mode | RFC‑A
Minimum | 0.0 | Maximum | 250.0
Default | 0.0 | Units | s
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 1
Coding | RW, BU

See PID1 Reference Source (14.003).

Parameter | 14.030 PID1 Pre-sleep Boost Level Enable
--- | ---
Short description | Enables the pre-sleep boost function
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default |  | Units |
Type | 1 Bit Volatile | Update Rate | Background write
Display Format | Standard | Decimal Places | 0
Coding | RO, ND, NC, PT

See PID1 Reference Source (14.003).

Parameter | 14.031 PID2 Output
--- | ---
Short description | Displays the output for PID2
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 2
Coding | RO, ND, NC, PT

See PID1 Output (14.001).

Parameter | 14.032 PID2 Feed-forwards Reference Source
--- | ---
Short description | Defines the input source for the feed-forwards reference source for PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, PT, BU

See PID1 Feed-forwards Reference Source (14.002).

Parameter | 14.033 PID2 Reference Source
--- | ---
Short description | Defines the input source for the reference for PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, PT, BU

See PID1 Reference Source (14.003).

Parameter | 14.034 PID2 Feedback Source
--- | ---
Short description | Defines the input source for the feedback for PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, PT, BU

See PID1 Feedback Source (14.004).

Parameter | 14.035 PID2 Reference Invert
--- | ---
Short description | Set to 1 to invert PID2 reference
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Reference Invert (14.005).

Parameter | 14.036 PID2 Feedback Invert
--- | ---
Short description | Set to 1 to invert PID2 feedback
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Feedback Invert (14.006).

Parameter | 14.037 PID2 Reference Slew Rate Limit
--- | ---
Short description | Defines the rate in change of output for PID2
Mode | RFC‑A
Minimum | 0.0 | Maximum | 3200.0
Default | 0.0 | Units | s
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 1
Coding | RW

See PID1 Reference Slew Rate (14.007).

Parameter | 14.038 PID2 Enable
--- | ---
Short description | Enables the use of PID2
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Enable (14.008).

Parameter | 14.039 PID2 Enable Source 1
--- | ---
Short description | Defines the input source for enabling PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, PT, BU

See PID1 Enable Source 1 (14.009).

Parameter | 14.040 PID2 Proportional Gain
--- | ---
Short description | Defines the Kp gain used for PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 1.000 | Units |
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Proportional Gain (14.010).

Parameter | 14.041 PID2 Integral Gain
--- | ---
Short description | Defines the Ki gain used for PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 0.500 | Units |
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Integral Gain (14.011).

Parameter | 14.042 PID2 Differential Gain
--- | ---
Short description | Defines the Kd gain used for PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Differential Gain (14.012).

Parameter | 14.043 PID2 Output Upper Limit
--- | ---
Short description | Defines the maximum value of the output for PID2
Mode | RFC‑A
Minimum | 0.00 | Maximum | 100.00
Default | 100.00 | Units | %
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 2
Coding | RW

See PID1 Output Upper Limit (14.013).

Parameter | 14.044 PID2 Output Lower Limit
--- | ---
Short description | Defines the minimum value of the output for PID2
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default | -100.00 | Units | %
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 2
Coding | RW

See PID1 Output Lower Limit (14.014).

Parameter | 14.045 PID2 Output Scaling
--- | ---
Short description | Defines the scaling factor of the output for PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 1.000 | Units |
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Output Scaling (14.015).

Parameter | 14.046 PID2 Destination
--- | ---
Short description | Defines the output parameter for PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, DE, PT, BU

See PID1 Destination (14.016).

Parameter | 14.047 PID2 Integral Hold
--- | ---
Short description | Enables the integral hold function for PID2
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit Volatile | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Integral Hold (14.017).

Parameter | 14.048 PID2 Symmetrical Limit Enable
--- | ---
Short description | Enables the symmetrical limit for PID2
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Symmetrical Limit Enable (14.018).

Parameter | 14.049 PID2 Feed-forwards Reference
--- | ---
Short description | Displays the value of the feed-forwards reference for PID2
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 2
Coding | RO, ND, NC, PT

See PID1 Feed-forwards Reference (14.019).

Parameter | 14.050 PID2 Reference
--- | ---
Short description | Displays the value of the reference for PID2
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 2
Coding | RO, ND, NC, PT

See PID1 Reference (14.020).

Parameter | 14.051 PID2 Feedback
--- | ---
Short description | Displays the value of the feedback for PID2
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 2
Coding | RO, ND, NC, PT

See PID1 Feedback (14.021).

Parameter | 14.052 PID2 Error
--- | ---
Short description | Displays the value of the error for PID2
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default |  | Units | %
Type | 16 Bit Volatile | Update Rate | 4ms write
Display Format | Standard | Decimal Places | 2
Coding | RO, ND, NC, PT

See PID1 Error (14.022).

Parameter | 14.053 PID2 Reference Scaling
--- | ---
Short description | Defines the scaling factor for the reference for PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 1.000 | Units |
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Reference Scaling (14.023).

Parameter | 14.054 PID2 Feedback Scaling
--- | ---
Short description | Defines the scaling factor of the feedback for PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 1.000 | Units |
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 3
Coding | RW

See PID1 Feedback Scaling (14.024).

Parameter | 14.055 PID2 Digital Reference
--- | ---
Short description | Defines the value of the digital reference for PID2
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default | 0.00 | Units | %
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 2
Coding | RW

See PID1 Digital Reference (14.025).

Parameter | 14.056 PID2 Digital Feedback
--- | ---
Short description | Defines the value of the digital feedback for PID2
Mode | RFC‑A
Minimum | -100.00 | Maximum | 100.00
Default | 0.00 | Units | %
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 2
Coding | RW

See PID1 Digital Feedback (14.026).

Parameter | 14.057 PID2 Enable Source 2
--- | ---
Short description | Defines the input source for enabling PID2
Mode | RFC‑A
Minimum | 0.000 | Maximum | 59.999
Default | 0.000 | Units |
Type | 16 Bit User Save | Update Rate | Drive reset read
Display Format | Standard | Decimal Places | 3
Coding | RW, PT, BU

See PID1 Enable Source 2 (14.027).

Parameter | 14.058 PID1 Feedback Output Scaling
--- | ---
Short description | Defines the scaling factor of the output feedback for PID1
Mode | RFC‑A
Minimum | 0.000 | Maximum | 4.000
Default | 1.000 | Units |
Type | 16 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 3
Coding | RW

PID1 alternative feedback and error selection

The description given in PID1 Output (14.001) assumed that PID1 Mode Selector (14.059) = 0 so that PID controller 1 uses its own feedback (FBK1). It is possible to select alternative configurations that allow various combinations of feedback or error from either PID controller to be used as shown below.

PID1 Mode Selector (14.059) can be used to select the feedback and error as shown in the table below. It should be noted that PID controller 2 will operate normally even when its feedback or error has been selected for PID controller 1. However, if PID1 Mode Selector (14.059) is non-zero PID controller 2 enable is controlled directly by the enable state of PID controller 1.

PID1 Mode Selector (14.059) | Feedback | Error
0: Fbk1 | FBK1 | ERR1
1: Fbk2 | FBK2 | ERR1
2: Fbk1 + Fbk2 | FBK1 + FBK2 | ERR1
3: Min Fbk | Lowest of FBK1 or FBK2 | ERR1
4: Max Fbk | Highest of FBK1 or FBK2 | ERR1
5: Av Fbk | (FBK1 + FBK2) / 2 | ERR1
6: Min Error | FBK1 | If |ERR1| ≤ |ERR2| then ERR1 Else ERR2
7: Max Error | FBK1 | If |ERR1| ≥ |ERR2| then ERR1 Else ERR2

PID1 Feedback Output Scaling (14.058) can then be used to scale the results. PID1 Feedback Square Root Enable 2 (14.062) can be used in converting the output of the combined feedback from pressure to flow. It is easier to use a pressure transducer than a flow transducer, and so the feedback from the transducer needs to be converted from pressure to flow. As flow = Constant x √Pressure the square root function can be used in the conversion.

Parameter | 14.059 PID1 Mode Selector
--- | ---
Short description | Defines the mode of PID1
Mode | RFC‑A
Minimum | 0 | Maximum | 7
Default | 0 | Units |
Type | 8 Bit User Save | Update Rate | Background read
Display Format | Standard | Decimal Places | 0
Coding | RW, TE

Value | Text
0 | Fbk1
1 | Fbk2
2 | Fbk1 + Fbk2
3 | Min Fbk
4 | Max Fbk
5 | Av Fbk
6 | Min Error
7 | Max Error

See PID1 Feedback Output Scaling (14.058).

Parameter | 14.060 PID1 Feedback Square Root Enable 1
--- | ---
Short description | Enables the squre root function of PID1
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Feedback Source (14.004).

Parameter | 14.061 PID2 Feedback Square Root Enable
--- | ---
Short description | Enables the squre root function of PID2
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Feedback Square Root Enable 1 (14.060)

Parameter | 14.062 PID1 Feedback Square Root Enable 2
--- | ---
Short description | Enables the squre root function of PID1
Mode | RFC‑A
Minimum | 0 | Maximum | 1
Default | 0 | Units |
Type | 1 Bit User Save | Update Rate | 4ms read
Display Format | Standard | Decimal Places | 0
Coding | RW

See PID1 Feedback Output Scaling (14.058).