Siemens SIMATIC NET PROFIBUS - Manual (Page 461)

7-1
PROFIBUS Optical Bus Terminal (OBT)
C79000-G8976-C122-02
Technical Specifications
Table 7-1 Technical Specifications
Technical Specifications
Power supply (safety extra–low voltage with reliable
isolation, SELV or complying with NEC Class 2) 24 VDC (18 V to 32 V)
Power consumption at 24 V input max. 200 mA
Transmission rate 12 Mbps, 6 Mbps, 3 Mbps, 1.5 Mbps, 500 Kbps, 187.5
Kbps , 93.75 Kbps, 45.45 Kbps, 19.2 Kbps, 9.6 Kbps
Transmission rate setting made automatically
Mode optical bus
Bit error rate <10 –9
Input channel 1 to channel 3
Bit length
Jitter 0.7 to 1.3 tBit
-0.03 to +0.03 tBit
Output channel 1 to 3
Bit length
Jitter 0.99 to 1.01 tBit
-0.003 to +0.003 tBit
Signal delay time (any input/output)
≤
6 tBit
Cascading depth of optical bus limited only by signal run time
Electrical channel
Input/output signal RS–485 level
Input dielectric strength -7 V to +12 V
Minimum current at 5V (for terminating resistors) 10 mA
Electrical isolation from 24V input Isolation due to function; not safety–related!
Optical channels
Optical source LED
Coupled optical power
– in plastic fiber 980/1000
– in PCF fiber 200/230
P
T(min)
P
T(max)
– 5.9 dBm +0.5 dBm
– 16 dBm –1.5 dBm
Receiver sensitivity
– with plastic fiber 980/1000
– with PCF fiber 200/230
P
R(min)
P
R(max)
–20 dBm 0 dBm
–22 dBm –2 dBm
7