REXROTH IndraDrive Fc FCS01, Operating Instructions Manual

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Rexroth IndraDrive FCS01.1 Control Communication - Field Busses and Protocols
15-45
DOK-INDRV*--FCS01*****-IB01_EN-P
Data Coding
Each telegram starts with the start character STX (= 02 Hex), followed by
the indication of length (LG) and the address byte (ADR). The use
characters follow after that. The telegram is completed by the data
storage character BBC (Block Check Character).
STX
LGE ADR N
1
N
2
...
N
n
BCC
With word information (16 bit) in the useful data record (= use character
record), the high byte (first character) is always transmitted first, followed
by the low byte (second character). For double word information, the
following applies analogously:
First, the high word is sent, followed by the low word.
Code Significance
STX (Start of Text): ASCII character: 02 Hex
The start character is the first character in the telegram; together with the start pause, it is used to
reliably identify the start of telegram
LG (Telegram length): 1 byte, contains the telegram length.
The telegram length information is located in the 2. byte of the telegram; it indicates the telegram
length in bytes, starting with the 3. byte. The length information is used to differentiate between
the different telegram types. The data receiver can use the length byte to check the number of the
characters to be received.
ADR (Address byte): 1 byte, comprises the slave address among other information
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
0 M BC | Address (0..30) |
The USIP address is in the 3. byte (data bits 0 to 4) of the telegram. Via the USIP address, the slave
device which is to transmit or receive data is addressed. Accordingly, each of the available 31
addresses (0 ... 30) can be represented by a maximum of one slave device. To this effect, the
respective address must be set in the slave device. Bit 5 and bit 6 have a special significance.
Bit 5 broadcast: By setting this bit, a so-called broadcast telegram can be activated. In a broadcast
telegram, the address bits 0 t 4 are not taken into consideration by the connected slave, i.e. the
transmitted master telegram is evaluated by all slaves. Contrary to a standard address, the slaves
do not transmit a respond telegram, as this would cause bus conflicts.
Bit 6 mirror: By setting bit 6, the converter returns the received telegram in identical fashion (for
commissioning).
N
1
... N
n
Use character: One byte each, contents depending on job
BCC 1 byte, data storage character (Block Check Character)
The checksum BBC is formed byte-wise over the whole telegram as an exclusive OR'd operation.
After the last net character, the result is BBC.
BCC = STX
XOR
LGE
XOR
ADR
XOR
N
1
XOR
....N
N
Fig. 15-60: Data Coding
Character Frame
Each transmitted character starts with a start bit (logic 0) and ends with a
stop bit (logic 1). 8 bits are transmitted (1 byte). Saving is performed via a
parity bit (even parity). Accordingly, 11 bits are transmitted per character.
Telegram structure