GE Industrial Solutions 6KCV300lNS - Manual (Page 31)

S
12.0 PARAMETERS HANDLING THE OPTION (DGF)
In order to handle the option DGF parameters two parameters are involved:
Parameter 5EFAh: command sent to DGF.
Parameter 5EFBh: reading of the parameter and DGF operation result.
For better undrestanding of this chapter see the DGF manual , in particularly the organization of the
parameters.
The handling of the errors is not mentioned in the following chapter, therefore the error causes
mentioned in this chapter make reference to the DGF communication.
The InterBus-S parameter 5EFAh is a Record made up of:
EL
1
2
3
4
ELEMENT
Command
V-PAR (Write Only)
LEN.
BYTE
1
1
2
4
MEANING
Operation which has to be carried out
by the DGF (reading/writing etc.)
DGF Parameter type
DGF parameter index involved in the
operation
Value to be written to the DGF
parameter (Only by wiriting)
This is a write only parameter: the access to this parameter is possible in the following ways:
In the case of writing DGF parameter all the elements have to be filled, that is 8 Bytes have to be sent:
for the elements with more than one Byte the filling order starts from the less significant Byte to the
most one.
In the case of reading DGF parameter the Parameter Value element has not to be filled; that is 4
Bytes have to be sent: even in this case for the elements
more than one Byte, the filling order
starts from the less Byte to the most significant one.
To correctly carry out the operation required, the exact number of necessary Bytes must be sent: every
attempt to access a single element (by using subindex different from 0), or with a wrong number
of Bytes (for example by carrying out a reading service sending also the DGF parameter value) is rejected
and the operation with a negative result; for this reason the subindex of the InterBus-S parameter
5EFAh must always be 0.