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6 Interfaces
The following chapters give detailed information about the available interfaces.
6.1
Interface RS422 (Option 4220) and RS232 (Option 2320)
Depending on order information the measuring system can be equipped with an RS422 or an RS232 interface.
Both variants use the same protocol and differ only in their level height. The data transfer has the following for-
mat:
9600 Baud
1 Start Bit
8 Data Bits
1 Stop Bit
No Parity
Data record:
The actual value will be transferred every 20 ms with the following data record:
02h
STX
xxh
ABS-Data
xxh
ABS-Data
xxh
ABS-Data
xxh
ABS-Data
xxh
ABS-Data
xxh
ABS-Data
03h
ETX
xxh
BCC
6.2
Interface SSI (Option SSB0 and SSG0)
Principle of the function: If the clock is not interrupted for the time Tm-T/2 (output of further 25 periods), the shift
register clocks once again the same data value (error recognition in evaluation).
Some encoders contain a Power Failure Bit (PFB):
With FMAX the PFB is always „low".
T
1
2
3
4
5
1 1 G23 G22 G21 G20 G19 G18 G17 G16 G15 G14 G13 G12 G11 G10 G9
PFB = Power failure bit
T
= Cycle duration of the clock signal
TM = Monoflop time >15 µs
Figure 5: Function of the SSI interface
The "block check sum" is an „Exclusive OR" of all data inclusive STX and ETX.
All values will be transferred in ASCII-format.
Not inverted SSI Clock
Non-inverted SSI-Clock
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
24 Bit
G8
G7 G6 G5 G4
+ 1 Power Failure Bit
- 12 -
Interfaces
Tm-T/2
G3 G2
G1 G0 PFB
0
1
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