Parameter group 75. Master-slave function

The master-slave function allows for implementing automatic functions such as speed synchronization. The RS485 interface or the system bus interface can be used as the communication link. P100 Setpoint source = Master SBus or P100 Setpoint source = Master RS485 must be set at the slave. The process output data PO1 – PO3 (P870, P871, P872) are automatically set by the firmware. A programmable terminal function "Slave free run." P60x digital inputs basic unit, it is possible to separate the slave from the master setpoint and switch to local control mode (like control signal source bipolar/fixed setpoint).

For the slave, the process data (P87x) are automatically assigned as follows:

• PO1 = Control word 1
• PO2 = Speed
• PO3 = IPOS^® PO data
• PI1 = Status word 1
• PI2 = Speed
• PI3 = IPOS^® PI data

P811 RS485 Group address or P882 SBus Group address must be set to the same value for master and slave. For master/slave operation via RS485 interface, set P811 RS485 Group address to a value greater than 100. For operation via system bus (e.g. master-slave operation), the bus terminating resistors at the start and end of the system bus must be activated.

• INFORMATION
• Setpoint specified via RS485:
• If the master specifies the setpoint for the slaves via RS485, MOVITRAC^® B takes over the master function in the RS485 interface after the parameter P750 slave setpoint has been set to "RS485 speed". The communication with MotionStudio is aborted after MOVITRAC^® B is activated as RS485 master, since it has only one RS485 interface.
• To re-establish connection to MotionStudio, set P750 slave setpoint to "MASTER-SLAVE OFF" again. Switch off both the 24 V backup voltage and the power supply voltage for MOVITRAC^® B for this purpose. Next, switch the 24 V backup voltage or the power supply voltage back on again. After power on, P750 slave setpoint can be set to another value using MotionStudio within a time frame of 30 seconds. P750 can be set to another value at any time using the FBG11B keypad (without having to switch voltage off and on again). Once you have the parameter P750 to "MASTER-SLAVE OFF", MotionStudio can operate as master on the RS485 interface again. MotionStudio can also be connected via a UOH/DFxxxx fieldbus gateway. In this combination, MOVITRAC^® B can function as a master on the RS485 interface.

Connection check

• System bus (SBus): P883 SBus timeout interval is in effect when there is a communication link via SBus. If P883 SBus timeout interval = "0", data transmission via SBus is not monitored.
• RS485 interface: A connection check is always in effect if the communication link takes place via the RS485 interface; P812 RS485 timeout interval does not have any function. The slave inverter must receive a valid RS485 telegram within the fixed time interval of t = 500 ms. If the time is exceeded, the slave drives will stop at the stop ramp and error message F43 RS485 timeout will be issued.

Overview of functions of master/slave operation

• P750 Slave setpoint
• P751 Scaling of slave setpoint