Burkert Type 8644 - Manual (Page 52)

48 - 8644/phoenix
S
YSTEM
D
ESCRIPTION
Depending on the programming and runtime environment, polling for the answer to a read and write is done
by this environment. The write/read combination is therefore sufficient.
Take care to ensure that you always obtain the answer with a read when communicating with the 16 bit long
object indices of the E/A modules. Otherwise, the DRV1 error code 80 B5 00 ("the module is busy") will
show on the next communication. In this case, this means that the answer from the last communication
still needs to be picked up. This will be waited for.
Communication is made for accesses to E/A modules via the DPV1 index 48, the object and sub index of
the E/A module is transferred integrally as part of the data field.
When communicating with objects which are deposited on the DPV1 field bus node itself, reading and
writing can be done with a sequence of 1 (2) steps, since the indices are only 8 bits long.
Read (Read/Polling)
1. a) Dispateching a read on slot x
b) Polling the answer onto the read
Write (Write/Polling - Read/Polling)
1. a) Dispatching a write on slot x
b) Polling the answer onto the write
Indices 2 to 5 are used for accesses to objects from the DPV1 field bus node.
Format of write and read accesses (request and response)
The format for all accesses (request and response, read and write) in DPV1 is:
<DPV1 Header> <Data (PCP/DPV1)>
The DPV1 header here always has the format: <DPV1-Dienst> <Slot> <DPV1-Index> <DPV1-Length>
In the event of an eroneous response the format
• in the event of an E/A module error
<DPV1-Service> <Slot> <DPV1-Index> <DPV1-Length> <Error-Data (PCP/DPV1)>
• in the event of a DPV1 error
<DPV1-Service> <Error-Decode> <Error-Code 1> <Error-Code 2>
The <Data (PCP/DPV1)> are optional according to service and are configured as summarized in the
following table.