Network Control and Monitoring
54
Step 7 – Control Test – Verify Network Host Can
Control
Inverter
If your network host computer successfully monitored the inverter’s operation in Step 6,
then achieving control capability from the network host in this step will be easy. First, it
is important to know how to change inverter control between local (keypad) control and
network control. Then you will be ready to control the inverter from the network.
Parameter Changes and Network Errors
– Note that changing “P Group” DeviceNet
parameter values in the inverter causes the inverter to reset and initialize its network
operations. If the DeviceNet host computer is scanning at that moment, the inverter will
cause a network time-out error when it initializes. So, you can avoid these network errors
by stopping the network scan activity before changing “P Group” parameter values.
Configuring for Network Control
– The configuration for network control depends on
several factors. Understanding the principles below will help simplify how network
control works:
• “Local control” refers to the inverter accepting Run/Stop commands from either its
keypad or input terminals [FW] or [RV], if configured. “Network control” refers to a
host computer remotely sending Run/Stop commands via a DeviceNet connection.
• A DeviceNet setting or signal at the inverter
enables
or
permits
network control. This
means that an operator or control system at the inverter can, at any time, take back
control of the inverter from a network host by disabling DeviceNet control.
• The inverter uses P_43 DeviceNet Control Enable for the primary method of control
selection. By default, P_43 = 1 (set to enable network control).
• Alternatively, you can assign the intelligent input terminal [DNT] Select DeviceNet.
Its ON/OFF states work the same way as P_43 settings. Note that when [DNT] is
assigned to an input terminal, the inverter ignores the P_43 setting.
The table below summarizes these network control principles.
Configuring Network Control of Inverter
No.
P_43 DeviceNet
Control Enable
[DNT] Select
DeviceNet
Control Method Description
1
P_43 = 1, Enable
(default setting)
(not assigned)
Inverter control may be done via network polled
I/O. Inverter automatically resumes local control
if network host sets Network Control bit = OFF,
or the network scan or connection is lost.
2
P_43 = 0,
Disable
(not assigned)
The inverter ignores network polled I/O control.
However, the network host can still monitor the
inverter via polled I/O, and it can use explicit
messaging to get or set parameter values.
3
—
[DNT] = ON
Same description as No. 1. (When [DNT] is
assigned, the inverter ignores P _43 setting.)
4
—
[DNT] = OFF
Same description as No. 2. (When [DNT] is
assigned, the inverter ignores P _43 setting.)
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