48
CTI Janus Programmable Automation Controller IOG
7.2
Profibus DP I/O
The CTI Janus controller supports Profibus DP I/O devices that comply with the Profibus DPV1 standard. The
following Remote Base Controllers can be used to allow CTI 2500 modules or Siemens SIMATIC Series 505
®
modules to be used on the Profibus network:
•
CTI 2500-RBC Profibus Remote Base Controller
•
Siemens SIMATIC
®
505-6870 Profibus Remote Base controller.
The CTI Janus controller can communicate with up to 64 Profibus slave devices, reading up to 244 bytes per slave
and writing up to 244 bytes per slave. The controller supports modular slaves with up to 128 modules per slave.
Profibus network baud rates up to 12Mb are supported. See
Janus Workbench
help for additional details.
NOTE
The actual amount of data that can be exchanged with a slave is dependent on the capability of the slave.
The total amount of data that can be exchanged is limited by the I/O capability of the controller model.
Network data rates may be limited by the network configuration.
7.2.1
Connecting to the Profibus Network
Cable Selection
The Profibus network attaches to the Profibus DP connector on the front panel of the CTI Janus controller using
shielded twisted pair cable. See
for a pinout diagram of the connector.
The following table specifies the characteristics of the cable.
Characteristic
Requirement
Impedance
135
–
165 ohms (3
–
20Mhz)
Capacitance
< 30pF/m
Resistance
<110
Ώ/km
Conductor Area
0.34mm2 (22 AWG)
Cable Diameter
0.34 mm
The following cables meet the Profibus DP cable specifications:
•
Belden 3079A
•
Belden 3079E (Hi-Flex)
The cable incorporates two color coded wires (red and green) surrounded by a shield. One wire is used for
Transmit/ (TX/RX +) and the other for Transmit/Receive (TX/RX -). The color used to connect to TX/RX+ is
arbitrary; however, the same color must be used throughout the system. Do not cross the TX/RX + and TX/RX
–
signals.
