AS-Interface
Profibus-DP
Subject to reasonable modifications due to technical advances.
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Only "standard identification bytes" with a maximum size of 16 bytes or words may be
used as identification bytes. If the data windows to be transmitted shall be bigger than
16 bytes or words, they have to be out together out of several "standard identification
bytes".
If the requested data field length is smaller than the one calculated out of the param-
eter telegram, the gateway will not take up any communication relationship with the
DP-master.
The maximum data field length for input respectively output data is 149 bytes with a
device with one AS-i Master and 160 bytes with a device with two AS-i Masters.
8.3
Professional Mode
All AS-i/PROFIBUS Gateways with 2 AS-i Masters and/or the advanced AS-i diagnos-
tics
1
have a third operation mode, which we call the professional mode. We recom-
mend the use of the professional mode instead of the older advanced mode.
The AS-i/PROFIBUS Gateways with 2 AS-i Masters only allow the use of the easy
mode or the professional mode. The AS-i/PROFIBUS Gateways (FMS/DP) only run
in the easy mode or the advanced mode.
The extended functionality of the advanced mode affords a more extensive configu-
ration of Profibus-DP. The I/O-window has to be enlarged for the additional data
(management commands and user memory). The length of the I/O-window depends
on the following factors:
• number of the AS-i slaves (number of input and output bytes)
• size of the management channel (0, 3 or 5 Bytes)
• number of the user memory bytes
Size of the Window for the AS-i Input and Output Data
The size of the window for the AS-i input and output data has to be adjusted to the
AS-i configuration (see chapter 8.3.3).
Transmission of Management Commands (0, 3 or 5 bytes)
With the management commands you can transmit acyclically additional AS-i data
like e.g. AS-i parameters or reading the LDS or also writing the AS-i Control flags e.g.
to start an AS-i Control program.
The management channel uses either 3 or 5 bytes. If the commands write LPS, read
LPS, read LAS, read LDS, read LCS, read communication errors, write LOS or read
LOS shall be used, the management channel has to have a length of 5 bytes because
these commands use 4 bytes of data.
The management channel is built up as follows:
1. these are all devices that were delivered since September 1998; these devices have the following feature string:
„*B..Dc..***.....“ oder „*B..Dc2.***.....“, * is a placeholder for various characters
(this string can be read with AS-i Control Tools with the command Master | Identity)
byte 0
byte 1 - 2 respectively 1 - 4
Profibus output data
command byte
output data
Profibus input data
mirrored command byte
input data
