YASKAWA HV600 Technical Reference page 731

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Bypass Control
To use external commands to set the frequency references and motor run/stop with serial communications, set these
parameters as specified by the application:
• b1-01 = 2 [Frequency Reference Selection 1 = Serial Communications]
• b1-02 = 2 or 8 [Run Command Selection 1 = Serial Communications or AUTO Command + Serial Run]
For more information about operation mode selection, refer to b1-01 and b1-02.
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Bypass Functions
Enable these functions during start-up:
• Start and Stop the Bypass
Set the Run Forward Command (BO 1) to run the bypass in the forward direction. Set the Run Reverse Command
(BO 2) to run the bypass in the reverse direction. Run/Stop Monitor (BI 1) shows the current run status of the
bypass. Forward/Reverse Monitor (BI 2) shows the current direction.
NOTICE: Damage to Equipment. Make sure that the motor direction is correct when you set b1-04 = 0 [Reverse Operation
Selection = Reverse Enabled]. Incorrect motor direction can cause damage to HVAC equipment.
• Lock the Bypass Panel
Locking the panel prevents the user from using the HAND and OFF keys locally at the bypass panel. Panel Lock
(BO 10) can be commanded to lock and unlock the panel.
• Digital Inputs
Multi-Function Input DI-3 (BO 5) to Multi-Function Input DI-7 (BO 9) are the physical digital inputs on the bypass
controller. The bypass programming determines their functions and you can use an external device, for example a
pressure switch, or the network to set these inputs. Refer to the section on Multi-Function Inputs (Z2-03 to Z2-07)
for detailed information about the use and programming of the multi-function inputs. You can use Multi-Function
input 3 Monitor (BI 15) to Multi-Function Input 7 Monitor (BI 19) to monitor the multi-function input status. The
Multi-Function Input # Monitor state is the logical OR of the serial command value (BO 5) to BO 9) and the state of
the external connection when enabled by Z3-12.
Note:
The multi-function inputs can be set by both external devices or over the network. Use caution when Z3-12 is enabled and when connecting
the multi-function inputs to external devices to ensure correct system operation.
• Digital Outputs
Multi-Function Output DO-7 (BI 10) through Multi-Function Output DO-9 (BI 12) are the physical digital outputs
on the bypass. The bypass programming determines their functions Refer to the section on Multi-Function Outputs
(Z2-23 ~ Z2-25) for detailed information about the use and programming of the multi-function outputs.
• Loop Gain
PI Proportional Gain (AO 4) and PI Integral Time (AO 5) are the gain and integral time parameters used by the
bypass. The PI loop is structured differently than the Metasys loop. Refer to the User Manual section on PID for
information on how the PI loop functions.
• Reading and Resetting Faults
The Fault Monitor (BI 4) and Bypass Ready Monitor (BI 3) show the current status of the bypass. The Fault Code
(AI 10) contains the code for the most current fault. The LST Fault Code (AI 19) contains the code for the previous
fault. Refer to Alarm Register Contents for descriptions of the fault codes. The bypass faults can be reset through
the Fault Reset Command (BO 4). The Fault Reset Command is only available when the Run Forward Command
and the Run Reverse Command are both OFF.
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Cable Loss Configuration and Behavior
This section describes the configurable cable loss feature of the bypass. This feature offers a user maximum flexibility
in determining bypass response to a loss of communication.
• Behavior at Loss of Communication
The bypass can be configured to respond to an interval without receipt of a message in one of these methods:
– Continue at last speed
– Continue at last speed with alarm
– Continue at preset speed
– Ramp to Stop with EF0 [Option Card External Fault]
YASKAWA SIEPYAIH6B01A HV600 AC Drive Bypass Technical Reference
10.5 Metasys N2 Communications
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