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Combining single IEC messages in an event object
Messages are transmitted as single messages (1 bit per messages) or double messages (2 bits per message) in IEC 870-5-101 protocol. Sometimes a number of single messages have to be interpreted as a bit combination. Therefore, ProWin® enables you to combine several IEC messages in an event object using PV groups and internal "auxiliary PVs".
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| Example: |
| ME_129.be000 |
(Single message, object number 129) |
| ME_130.be000 |
(Single message, object number 130) |
| ME_131.be000 |
(Single message, object number 131) |
| ME_132.be000 |
(Single message, object number132) |
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Messages ME_129 and ME_130 are to form a new PV called Objekt-1.bi000.
Messages ME_131 and ME_132 are to form a new PV called Objekt-2.bi000.
The procedure is the following: |
| Step 1: |
You configure two internal binary PVs called Object-1 and Object-2. |
| Step 2: |
You configure two PV groups called PV-GR1 and PV-GR2. Next you assign the PVs ME_129 and ME_130 to PV-GR1 and the PVs ME_131 and ME_132 to PV-GR2.
The assignment number corresponds to the bit position. Initial bit position is always 0..
Note:IEC double messages allocate two subsequent bits. |
| Schritt 3: |
The PV-groups are linked with the internal PVs with an instruction list.
The IL consists of one operation only.
The PV group "PV-GR1" is used as an initial condition for the instruction list. IL has to be executed with positive and negative slopes of the PV group. |
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Step 3 is to be done correspondingly for object 2.
Variation
If you additionally combine the single PVs in a general PV group, you can use the latter as a PV group for a general IL link. I.e. you don´t have to define a new IL link for each object, but you are able to combine all objects in one IL. This one consists of a number of sequences then:
RCV PV-GR1 Objekt-1.bi000
RCV PV-GR2 Objekt-2.bi000
etc.
Note:
The PV names and PV group names are only sample names. They may be chosen freely according to the assignment rules for PV names. |
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