Table 16:
Control bits
Setting column
Alternatives
Description
Bit address
Empty
Control point is not in use. It can
be edited with Enter
keys.
1...65535
Control point is not in use on this
Coil (0x) address. This is a write-
only coil. A (read-only) indication
can be mapped to the same coil
address, without the two objects
interfering one another.
Control struct number
Not adjustable
0: Control structure not defined.
1...N: Control structure number
defined.
Control struct bit
Not adjustable
0...15: Bit definition within the
Control structure.
The bit address is configurable. It is also possible to completely remove a control point
from the Modbus 0x memory map by first deleting the address and then pressing
ENTER.
Modbus controls have been defined for all controllable switchgear and generic control
functions. The easiest way to prevent unwanted remote operations is to remove the
control points from the memory map. Generic control points might be in use for
internal purposes by the relay configuration. In such case effects can be harmful if the
same points are simultaneously written from the communication.
The Modbus controllable write-only coil point definitions are separated from the read-
only coil point definitions. It is possible to define a write-only object X and a read-only
object Y to the same 0x coil bit address Z. While this may be a violation of the 0x
Modbus area intention in some cases, it is safe from the relay's point of view. It means
that reading of 0x coil address Z returns the value of object Y, and writing to 0x coil
address Z activates the object X.
In the configuration example, a physical output on coil address 100 needs to be
controlled. The state of the physical output should be readable from the same coil
address 100.
1MRS757645 B
Section 3
Vendor-specific implementation
620 series
37
Communication Protocol Manual
