Extension Board for MODBUS on SMARTCON Control Unit
DS-ENGLISH-MODBUS-V2.01-2019.05.15
SEC-DS-GERMAN-MODBUS-RTU-V2.01-2019.05.15
Extension Board for MODBUS-RTU on SMARTCON Control Unit
1
General Information
For SCHIEBEL ACTUSMART or SMARTCON actuators the standardized fieldbus interface MODBUS-RTU is
available.
This interface is a product option represented in hardware on the device, thus making it beneficial to advertise
intended use upon ordering.
Although enabling MODBUS-RTU a posterior is possible, such upgrades should only be performed by autho-
rized SCHIEBEL engineers or specially trained personnel.
MODBUS-RTU determines technical and functional characteristics of the serial fieldbus system used to con-
nect distributed autonomous devices. MODBUS-RTU distinguishes Master- and Slave-Devices and has been
designed for data-transmission on field-level, hence, the communication of central control units - as SPS or PC
- with decentrale field-devices over a fast serial connection.
Communication functionality is standardized by the MODBUS Organization (modbus.org).
The
physical communication layer
is based on a RS-485 interface connected through a shielded twisted
two-wire cable.
SCHIEBEL Actuators ACTUSMART or SMARTCON are always slave devices.
Communication settings
The detection of the settings of the Modbus RTU communication is done automatically in the SCHIEBEL
MODBUS-RTU slave module during communication start-up.
The supported baud rates are:
4800 bps, 7200 bps, 9600 bps, 14400 bps, 19200 bps, 28800 bps,
38400 bps, 57600 bps, 76800 bps, 115200 bps
The byte frame has following bits:
1 start bit
8 data bits, LSB first
1 parity bit (even, odd or mark)
1 stop bit
If mark parity is not supported by the MODBUS-RTU master, you can use no parity and 2 stop bits instead.
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Connection
Depedning on the order there are the following connections possible:
•
standard design: connection board
•
explosion proof design: terminals
2.1
Standard design
Connecting the actuator to the fieldbus system is accomplished through connecting the bus cable to the con-
nection print in the connection compartment of the actuator. Thus for convinience, the MODBUS-RTU con-
nector is pluggable like every other external connector for signal or power on our actuators. Disconnecting
a device will have no effect on the communication of other devices in the same strand. Meaning, the net-
work maintains full functionality if a device is disconnected while the network is in operation. But beware: At
the end of each strand MODBUS-RTU has to be terminated. This termination can either be performed by
a SMARTCON-Actuator or a separate active bus termination device. Note that the power for the termination
resistors of SMARTCON-Devices comes from the actuator. Hence, disconnecting the terminating SMARTCON
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