Burkert Type 8644 - Manual (Page 49)

8644/phoenix - 45
S
YSTEM
D
ESCRIPTION
DPV1 is the expansion of the cyclical data exchange according to IEC61158 to acyclical services.
Complex devices can be operated easily with this expansion. Acyclical data are particularly suitable for
data which do not have to be transmitted on a regular basis or are of variable length, as is the case for
example with an RS232 interface.
The following differences can be found:
1. Acyclical communication via the category 1 master (C1 master)
The C1 master carries out the parameterization during slave start-up and is master in the cyclical data
traffic. If it necessary to use an RS232 interface acyclically from the C1 master or to read a parameter
optionally from the device, corresponding write and read accesses are defined. Since the C1 master is
already connected to the slave in the cyclical data traffic, no explicit connection is established, but
direct communication can be made with the slave via read and write.
2. Acyclical communication via the category 2 master (C2 master)
The C2 master can be realized in various forms, for example in the form of a display device or control
terminal. In the display device, data is fetched by the slave only on request, for example (if a certain
parameter is to be read), while accesses are acyclical in the control terminal. Accordingly, write and read
accesses are provided for the C2 master. Since the C2 master does not communicate in the cyclical
traffic, it must establish and cut the connection explicitly.
3. Acyclical communication in cyclical data exchange (C1 master)
DPV1 is still relatively new. In contrast, the service life of controls and facilities is very long, so that
expansions and retrofits can take place. Often, controls are not yet DPV1 compatible, but should be
able to operate complex participants. This problem is solved by using the acyclical services within the
process data too. That is to say, a control which has no command of DPV1 can control more complex
interfaces such as RS232 or HART (via IB IL AI 2/HART) straight away.
Examples
Example module IB IL RS232
Configuration of 8644-DPV1 ME02 (Profibus – DPV1-field bus node) – IB IL 24 DI 8 – IB IL 24 DO 8
station – IB IL RS232 - IB IL AI 2/SF – IB IL AO 1/SF
Screenshots created using STEP7, V5.2, Service Pack 1
Object directories:
A Number of elements
L Length of one element in bytes
rd Read access allowed
wr Write access allowed
Index Data type A L Relevance Object name Rights
5FC1h Var of Unsigned 8 1 1 Module launch indicator SART-IND rd/we
5FE0h String Var of Octet String 1 58 V24 data V24 data rd/we
5FFFh Arry of unsigned 8 20 1 Configuration of the terminal INIT-TABLE rd/we
Description of field bus node