INFICON BCG450-SP ATM to Ultra-High Vacuum Triple Gauge (Profibus) - Manual (Page 9)

tira41e1 (2005-06) BCG450SPv1.cp
9
The structure of the parameter channel is described in the table below.
The parameter channel (called PKW Interface hereinafter) consists of 8 bytes.
Octets
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.
The instruction and response are represented in the first two bytes (PKE) of the
parameter channel:
Bit position
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
AK res. Slot
Where: Bits Meaning
15 … 12 AK
Instruction/response signature
11 … 8 Reserved
7 … 0 Define the slot from which data are read or onto which a
value is to be written
In Master
⇒ Slave communication, the AK field contains the instruction signature of
the master.
In Slave
⇒ Master communication, the AK field contains the instruction signature of
the slave.
AK Function
Master
⇒ Slave
(Instruction signature)
AK
normal
Function
Slave
⇒ Master
(Response signature)
AK
error
0 No instruction 0 No response
1 Read parameter value 1
2
11
Transmit parameter value
(word)
Transmit parameter value
(double word)
Transmit parameter value
(byte)
7
1)
2 Write parameter value
(data type: word) 1 Transmit parameter value
(word) 7
1)
3 Write parameter value
(data type: double word) 2 Transmit parameter value
(double word) 7
1)
10 Write parameter value
(data type: byte) 11 Transmit parameter value
(byte) 7
1)
1)
Instruction cannot be executed (error code)
On the left of the table, the instruction signatures of the master are listed according
to their function. On the right of the table, the corresponding normal responses (AK
Normal) and error codes (AK Error) transmitted by the slave are listed.
2.2.1 Parameter Channel
2.2.1.1 PKE Parameter
Signature Value
Instruction signature