Yaskawa iQpump Controller Programming Manual User Manual
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YASKAWA TM.iQp.07 iQpump Controller Programming Manual
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iQpump MEMOBUS / Modbus Multiplex
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MEMOBUS / Modbus Multiplex
In order to run and control networked pumps, multiplexing needs to be implemented
After the iQpump memobus network is established, it will continually look for a drive that is ready to run (has Auto mode run, and not
faulted). It will command that drive to run in PI (thus becoming the lead drive) so that it can regulate the system pressure. When the
pressure is too low that it can no longer be maintained, the lead drive will attempt to pass the lead responsibility either to the next
available or to drive with the lowest runtime. The previous lead drive becomes a lag drive and will run at either PI regulation or a set
frequency thus making the new lead drive regulate the system pressure. This process is referred to as staging.
If the system pressure gets too high that a drive needs to shut down (unless it's the only drive left), the lead drive will attempt to shut off
and pass the lead responsibility back to the previous drive. This process is referred to as de-staging.
The selection of the new lead drive depends on the setting of a new parameter, P9-01 (Lead Drive Selection). When P9-01 = 0, the next
lead drive will be the next drive that the iQpump MEMOBUS / Modbus network has detected during its drive discovery scan. When P9-
01 = 1, the next lead drive will be the drive with the lowest run-time based on U1-13 (affected by o2-07 and o2-08).
Since the iQpump MEMOBUS / Modbus network uses monitor U1-13 when P9-01 = 1 (Lowest Runtime), lead drive selection is thus
directly affected by o2-07 and o2-08. It is recommended to keep o2-08 = 1 (Running Time). It should be noted that when U1-13 goes past
65535 hours, it gets reset to zero.
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Function Description:
<0034>
When P1-01 = 3 (Pump Mode = MEMOBUS / Modbus Network), issuing an Auto mode run will add it to the list of networked drives
that are available to run. At system start-up, the iQpump MEMOBUS / Modbus network will look for a drive available to run based on
parameter P9-01 (Lead Drive Selection). If there's an available drive, it will send a network command to run it as a lead drive (running in
PI). When P9-29 Net Start Delay is greater than 0.0s and the system is stopped, the system will wait the P9-29 setting after the first Auto
mode drive has been detected. This will allow other drives to be put on Auto mode and be considered for lead selection. All the drives in
the system will show a Net Start Dly message when the timer is still counting.
The P9-01 parameter is always used when there is a network request to stage.
A setting of “0: Next Available”, will look for the next drive ready-to-run in the network queue which is based on when the drive was
detected in the network. If the search reaches the end of the queue without finding a suitable drive, it will loop around to the first detected
drive.
shows an example of how the lead-lag operation will work for this setting.
A setting of “1: Lowest Runtime” will look for the drive that is ready-to-run on the network that has the lowest runtime (based on
monitor U1-13, which is affected by parameters o2-07 and o2-08).
shows an example of how the lead-lag operation will work
for this setting.
Parameter P9-05 (Lag Drive Mode) defines how lag drives function: running in either PI regulation or fixed speed. If P9-05 = 0, anytime
the drive shifts from being a lead to a lag, the drive will hold the current speed for the time set in P9-07 and then force it to the P9-06
level. If P9-05 = 1, the lag drive will continue to regulate its speed based on the PI conditions. This setting is not commonly used and
could result in an unstable system if not properly adjusted. If P9-05 = 2, the drive will turn off when the drive shifts from being a lead to
a lag and becomes available for the system to run as a lead again.
The lead drive uses parameters P9-08 to P9-11 to determine if it needs to stage, and parameters P9-12 to P9-15 to determine if it needs to
de-stage. Staging will request for a new lead drive and make the current one a lag drive. A stage request is only made when there are
drives available to run and the number of drives running is below P9-23. De-staging will make the previous lead drive (which is now a lag
drive) a lead drive once again, and stops the current lead drive. A de-stage request is only made when there are 2 or more drives running.
With this setup, there can only be 1 lead drive on the network at any given time. A quick de-stage function is invoked when high feedback
(based on P1-09 and P9-18) is detected for 2 seconds.
Staging:
P9-08 = 0: Output Frequency:
This mode monitors the lead drive output frequency and determines if staging is needed to maintain the setpoint. If the output frequency
of the lead drive rises above the P9-09 level for the time set in P9-11, the drive will issue a network stage request if there is a drive
available to run. Refer to
P9-08 = 1: Feedback Level:
This mode monitors the feedback level and determines if staging is needed. If the difference in setpoint and feedback (setpoint -
feedback) has exceeded the P9-10 level for the time set in P9-11, the lead drive will issue a network stage request if there is a drive
available to run. Refer to