IEC104. The 'Command' Tag
That tag is provided to transfer information about a process in the control direction; an access type is WriteOnly.
Specific parameters of the Command tag are set in the Protocol settings section:
IOA – IOA, an information object address
ASDU address (-1 – use ASDU address of device) – ASDU address
Command type:
45 – 1-element command
46 – 2-element command
47 – stepwise control command
48 - set-point command, normalized value without time tag.;
49 - set-point command, scaled value without time tag;
50 - set-point command, short floating point value without time tag;
51 - Bitstring of 32 bits without time tag;
58 – 1-element command with the timestamp CP56Time2a;
59 – 2-element command with the timestamp CP56Time2a;
60 – stepwise control command with the timestamp CP56Time2a;
61 - set-point command, normalized value with CP56Time2a;
62 - set-point command, scaled value with CP56Time2a;
63 - set-point command, short floating point value with CP56Time2a;
64 - bitstring of 32 bits with CP56Time2a;
Command duration:
0 – there is no an extra definition of duration of an output pulse
1 – short pulse (duration is defined by a system parameter)
2 – long pulse (duration is defined by a system parameter)
3 – persistent output
Select(true)/Execute(false) – when you request the Execute device immediately executes the command. When a Select is requested, the device sends a confirmation request, and only after confirmation from the OPC server does the command execute.
Other tag parameters are standard ones (see The Dialog of Tag Parameters ).