IEC104. The 'Value' Tag
That tag is provided to receive values from a device (information about a process in the control direction); an access type is ReadOnly.
The following command types are supported (a command is automatically defined, depending on the Data type in server parameter):
1:DIGITAL SINGLE (M_SP_NA_1) – one element (bit)
2:DIGITAL SINGLE WITH TIME (M_SP_TA_1) - one element (bit) with timestamp
3:DIGITAL DOUBLE (M_DP_NA_1) – two elements (bits)
4:DOUBLE-POINT INFORMATION WITH TIME (M_DP_TA_1) - two elements (bits) with timestamp.
5:STEP POSITION (M_ST_NA_1) – information about position of taps (7 bits)
6:STEP POSITION WITH TIME (M_ST_TA_1) – information about position of taps (7 bits) with timestamp.
7:BIT STRING OF 32 BIT (M_BO_NA_1) - bitstring of 32 bit.
8:BIT STRING OF 32 BIT WITH TIME (M_BO_TA_1) - bitstring of 32 bit with timestamp.
9:ANALOGIC NORMALIZED (M_ME_NA_1) – integer normalized
10:ANALOGIC NORMALIZED WITH TIME (M_ME_TA_1) – Measured value, normalized value with timestamp.
11:ANALOGIC CONVERTED (M_ME_NB_1) – integer converted
12:ANALOGIC CONVERTED WITH TIME (M_ME_TB_1) – целое преобразованное с меткой времени.
13: ANALOGIC FLOATING POINT (M_ME_NC_1) – real number floating-point
14:ANALOGIC FLOATING POINT WITH TIME (M_ME_TC_1) - measured value, short floating point value with with timestamp
15:INTEGRAL SUM (M_IT_NA_1) - integrated totals.
16:INTEGRAL SUM WITH TIME (M_IT_TA_1) - integrated totals with timestamp.
17:EVENT OF PROTECTION EQUIPMENT WITH TIME ( M_EP_TA_1) - event of protection equipment with timestamp.
18:PACKED START EVENTS OF PROTECTION EQUIPMENT WITH TIME (M_EP_TB_1) - packed start events of protection equipment with timestamp
19:PACKED OUTPUT CIRCUIT INFORMATION OF PROTECTION EQUIPMENT WITH TIME (M EP TC 1) - packed output circuit information of protection equipment with timestamp
20:PACKED SINGLE-POINT INFORMATION WITH STATUS CHANGE DETECTION(M_SP_NA_1) - packed single-point information with status change detection
21:MEASURED VALUE, NORMALIZED VALUE WITHOUT QUALITY DESCRIPTOR(M_ME_ND_1) - measured value, normalized value without quality descriptor
IOA with long timestamp CP56Time2a:
30: DIGITAL SINGLE WITH LONG TIME TAG (M_SP_TB_1) – one element (bit) together with timestamp
31: DIGITAL DOUBLE WITH LONG TIME TAG (M_DP_TB_1) – two elements together with timestamp
32: STEP POSITION WITH TIME TAG (M_ST_TB_1) – information about position of taps (7 bits) together with timestamp
34:MEASURED VALUE, NORMALIZED WITH TIME TAG (M_ME_TD_1) – integer measured normalized, together with timestamp
35:MEASURED VALUE, SCALED WITH TIME TAG (M_ME_TE_1) – integer measured scaled, together with timestamp
36:MEASURED VALUE, FLOATING POINT WITH TIME TAG (M_ME_TF_1) – real number measured together with timestamp
37:INTEGRATED TOTALS WITH TIME (M_IT_TB_1) - integrated totals with timestamp.
38:EVENT OF PROTECTION EQUIPMENT WITH TIME (M_EP_TD_1) - event of protection equipment with timestamp.
39:PACKED START EVENTS OF PROTECTION EQUIPMENT WITH TIME (M_EP_TE_1) - packed start events of protection equipment with timestamp
40:PACKED OUTPUT CIRCUIT INFORMATION OF PROTECTION EQUIPMENT WITH TIME (M_EP_TF_1) - packed output circuit information of protection equipment with timestamp
Note. Time-stamped variables can be written to the HDA archive. To do this, the setting "HDA access" must be enabled for the variable. If the "Auto writing" setting is set to False, then only the values that came with a time stamp will be recorded in the archive, but if the setting is set to True, then the values that came without a time stamp will also be written to the archive (they can be generated, for example, from a general poll)
The response frame of the IEC104 protocol contains special fields - based on these fields, the OPC server generates an quality attribute.
Quality bits IEC104 |
OPC Quality |
Desription |
IV (Invalid ) |
OPC_QUALITY_UNCERTAIN |
Value is not correctly |
BL (blocked) |
OPC_QUALITY_OUT_OF_SERVICE |
The value of information object is blocked for transmission |
SB (Substituted) |
OPC_QUALITY_LOCAL_OVERRIDE |
The value of the information object is provided by the input of an operator (dispatcher) or by an automatic source. |
NT (Not Topical) |
OPC_QUALITY_LAST_KNOWN |
The value was not updated within the specified time interval or is not available |
Specific parameters of the Value tag are set in the Protocol settings section:
IOA – IOA, an information object address
ASDU address (-1 – use ASDU address of device) – ASDU address
Read by command 102 - tag polling will be performed by the command <102>: C_RD_NA_1, if such polling is enabled in the device settings.
Other tag parameters are standard ones (see The Dialog of Tag Parameters ).