INFICON BPG402-SP ATM to Ultra-High Vacuum Gauge (Profibus) - Manual (Page 8)

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tira47e1 (2005-08) BPG402SPv1.cp
In Data Exchange mode, the DP master class 1 cyclically transmits data from and
to all slaves that are connected to the bus.
In this document, data transmitted from the slave to the master are called "input
data" and data transmitted from the master to the slave are called "output data".
The input and output data of the BPG402-SP has two logic parts:
1) the parameter channel
2) the process data channel
There is a number of standard telegrams, consisting of:
a) the parameter channel only
b) the process data channel only
c) both, the parameter and process data channel
The parameter channels allows masters without Profibus DPV1 to access device
specific parameters that are not part of the normal cyclic data telegram. For mas-
ters with Profibus DPV1, no parameter channel is required.
The input data (transmitted by the BPG402-SP) consists of the 8 bytes of the pa-
rameter channel (if there is a parameter channel in the standard telegram) and of
up to 15 bytes of process data depending on the selected standard telegram.
Byte Byte
1 2 3 4 5 6 7 8 9 … 23
Parameter Channel Process Data
PKE IND res. PWE
Where: PKE = Parameter Signature Value Reading or writing com-
mand and definition of the slot
IND = Sub Index Index No. of the index to be
read (
→ "Block Model")
res. = reserved
PWE = Process Value Value to be read or written
The output data (transmitted by the master) consist of 8 bytes of the parameter
channel and up to 10 bytes of process data (control bytes).
Byte Byte
1 2 3 4 5 6 7 8 9 … 18
Parameter Channel Process Data
PKE IND res. PWE
The structure of the parameter channel is described in the table below.
The parameter channel (called PKW Interface hereinafter) consists of 8 bytes.
Byte
1 2 3 4 5 6 7 8
PKE IND res. PWE
The PKW Interface allows reading and writing of slave parameters with a maximum
data length of 4 bytes. Strings cannot be read.
The slave generates exactly one response per instruction transmitted by the mas-
ter. The instruction and response cannot be blocked. This means that exactly one
instruction per output telegram can be transmitted to the slave and that exactly one
response per input telegram can be transmitted to the master. 4 bytes of actual
data can thus be transmitted at a time.
2.2 Structure of the Cyclic
Data Telegrams in
Data Exchange Mode
Input data
Output data
2.2.1 Parameter Channel