Start-Up  09.02 
4-72  Siemens AG    6SE7087-6AK85-1AA0 
  Rectifier/Regenerating Unit    Operating Instructions 
4.5.5  Sequence of operations for starting up the SCB2 board: 
  1  With the power supply disconnected, insert the SCB2 board into slot 2 (or, if you have installed a 
technology board, into slot 3). 
 
2  The following parameters are important for operation (for details, see parameter list in Section 5 and 
operating instructions for the SCB2): 
- P682  SCB protocol 
Selection of operating mode for the SCB2 interface 
- P683.2  SCB bus address 
Selection of bus address at which the SCB2 can be addressed via the USS bus (P682 = 1 or 2) 
- P684.2  SCB Baud rate 
Selection of transmission rate with which the USS interface (P682 = 1 or 2) or peer-to-peer 
interface (P682 = 3) of the SCB2 should be operated 
- P685.2  SCB PKW number 
Selection of number of words (16 bit) of the PKW part in the net data block of the USS telegram 
(P682 = 1 or 2) 
- P686.2  SCB PZD number 
Selection of number of words (16 bit) of the PZD part in the net data block of the USS telegram 
(P682 = 1 or 2) 
- P687.2  SCB telegram failure time 
Selection of telegram failure time for the USS or peer-to-peer protocol 
- P689.2  SCB peer forwarding 
Identifies words in the received peer-to-peer telegram that should be forwarded immediately 
- P690i  SCB actual values 
Selection of parameter values that should be transmitted via the serial interface of the SCB2 
board 
- r730i  SCB diagnosis 
SCB diagnostic information 
- P090 or P091 for logging the board 
- The display parameter r730 (diagnostic information) assists in the correction of problems during 
commissioning. 
 
 
3  Switching off and on of the electronics supply voltage. Doing this causes the values of the parameters 
listed above to be transferred from the supplementary board. 
 
The optional board SCB2 (Serial Communication Board 2) provides an additional serial interface using 
either the USS or peer-to-peer protocol. 
With the USS protocol, up to 31 slaves (converters) can be controlled by a master. In this case, the bus 
terminating resistors on the last bus node must be connected by closing the switch S1 in order to prevent 
transmission faults. 
The peer-to-peer protocol allows data to be forwarded quickly from unit to unit (e.g. for implementing a 
setpoint cascade). 
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