NORD USS and Modbus RTU Manual
30
Subject to technical amendments
BU 0050 GB-3111
1.5.3.3
Control word (STW)
The control word (STW) is the first word transferred to the frequency inverter in the process data area in an
order telegram. For example, a control word "Ready for switch-on" corresponds to 047E
(hex)
.
PZD1
PZD2
PZD3
PZD4
STW
SW1
SW2/3
SW2/3
15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Bit
Value
Meaning
Comments
0
0
OFF 1
Reverse with the brake ramp, with disconnection from supply at f=0Hz
1
ON
Ready for operation
1
0
OFF 2
Cut off voltage; the inverter output voltage is switched off; the FI enters a state
where switching on is disabled.
1
Operating condition
OFF 2 is cancelled
2
0
OFF 3
Quick stop with programmed quick stop time; with disconnection from supply at
f=0Hz; the FI switches to starting disabled condition.
1
Operating condition
OFF 3 is cancelled
3
0
Disable operation
Cut off voltage; the inverter output voltage is switched off; the FI enters a state
where switching on is enabled.
1
Enable operation
The output voltage is enabled; ramp to the existing setpoint
4
0
Lock ramp generator
Ramp generator is set to zero; no disconnection from supply at f=0Hz; FI remains
in the operation enabled state.
1
Operating condition
Enable ramp generator
5
0
Stop ramp generator
The setpoint currently provided by the ramp generator is "frozen" (frequency is
maintained).
1
Enable ramp generator Enable setpoint on ramp generator
6
0
Disable setpoint
Selected setpoint value is set to zero on the ramp generator.
1
Enable setpoint
Selected ramp generator setpoint is activated.
7
0
No acknowledgement
With the switch from 0 to 1, errors which are no longer active are acknowledged.
1
Acknowledge
Note: When a digital input has been programmed for the "ack.fault" function, this
bit must not permanently be set to 1 via the bus (otherwise, edge evaluation
would be prevented).
8
0
1
Bit 8 active
Bus bit 8 from the control word is set. (Only for SK 200E and SK 500E)
For further details of the function please refer to parameter (P480).
9
0
1
Bit 9 active
Bus bit 9 from the control word is set. (Only for SK 200E and SK 500E)
For further details of the function please refer to parameter (P480).
10
0
PZD invalid
The transmitted process data is invalid.
1
PZD valid
Valid process data is transferred from the master.
Note:
If setpoints only are transferred via the bus, this bit must be set so that the
transferred setpoint is valid.
11
0
1
Rotational direction:
right
Rotational direction right (priority) ON*
12
0
1
Rotational direction:
left
Rotational direction left ON*
13
0/1
Reserved
14
0/1
Bit 0 to switch
parameter set
00 = Parameter set 1
01 = Parameter set 2
10 = Parameter set 3
11 = Parameter set 4
15
0/1
Bit 1 to switch
parameter set
* If Bit 12=0, then "Direction of rotation right ON" applies
Table 14
