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Appendix A.13. DnpSubType
DNP objects often contain more than one element of information, e.g. Object 30, variation 1 is a 32- bit analog input. When the DNP device is polled for data for this object the device returns a data structure which contains a 32 bit value for the input and an 8 bit status byte indicating the input’s quality. Alternatively the FieldServer defaults to the value subtype.
By using the value or flags in the field for dnpSubType you could have the FieldServer extract the value or the status byte and place them in the data array associated with the Map Descriptor. In this example it would have made no sense to try and extract a time as there is no time field associated with object 30, variation 1.
| Permitted Values |
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| Value |
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| The driver extracts the value of the object being read. |
| Flags |
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| The driver extracts the quality/status byte of the object. |
| Time1 |
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| The driver extracts the time field from the object. |
| Time2 |
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| The driver extracts a second time field from the object if the object has more |
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| than one. | |
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| Used with a write Map Descriptor with the dnpFunction set to 5 (Direct |
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| Operation with no Ack). The driver uses multiple consecutive elements from |
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| the data array to build the write command. |
| Combo |
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| When used with Object 12 Variation 1. |
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| The 1st array element is used as a byte to fill in the control code field. | |
| (NB - only valid with |
| The 2nd array element is used as a byte to fill in the count field. | ||
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| The 3rd array element is used as a UINT32 to fill in the on time field. | |||
| Object | 12, | Variation |
| The 4th array element is used as a UINT32 to fill in the off time field. |
1; |
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| The status field is always set to zero. | |
| Object | 41, | Variation |
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1 & 2) |
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| When used with Object 41 Variation 1 & 2 | |
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| The 1st array element is used as a INT32 (variation 1) or INT16 (variation2) |
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| to fill in the requested value field. |
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| The 2nd Array Element is used as a byte to fill in the control status field. (See |
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| the definition of object 12 for a description of this field.) |
Appendix A.14. Communication Stats
The driver counts bytes on the connection and messages on the Map Descriptors. Thus if a Map Descriptor is used to generate a poll then the transmit messages increment and when a response is received, its received messages will increase. The byte count of these messages will be counted on the connection and not on the Map Descriptor. The connection also counts messages and bytes that form connection related messages such as link resets, confirms, acks, naks….
Appendix A.15. Link Reset
The Link Reset message forms part of the Data Link layer of the DNP 3.0 protocol. It is used to establish and check a connection. When configured as a Client, the driver sends a Link Reset and waits for the Server to respond before starting data transfer. When configured as a Server, the driver will not respond to messages until the remote Client has sent a Link Reset. The following example configuration will override this default behavior.
Example
// Server Side Connections |
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Connections |
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Port | ,Baud | ,Parity | ,Protocol | ,Application |
P8 | ,9600 | ,None | ,DNP | ,NoLink |
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