Cuadros

Bus and network modules
UNI-TELWAY bus Characteristics
References : pages 42702/6 and 42702/7

Characteristics
Structure Nature Physical interface Access method Transmission Mode Data rate Medium Configuration Number of devices Length of bus Tap links Services UNI-TE Heterogeneous industrial bus RS 485 Master-Slave Asynchronous transmission in baseband 9.6 K bits/s, which can be configuredon certain devices for 1.2 to 19.2 K bits/s Screened double twisted pair 28 devices maximum (1) 255 datalink addresses (one device can occupy several addresses) (2) 1000 m maximum excluding tap links 20 m maximum Maximum message size TSX/PMX model 40 128 bytes TSX 17-20 32 bytes TSX 47-20/25 32 bytes TSX Nano Terminal port 128 bytes TSX Micro/Premium PCMCIA card Terminal port 240 bytes 128 bytesPoint-to-point requests with confirmation (question/response) initiated by any connected device Unsolicited point-to-point data, without confirmation, initiated by any connected device Broadcast messages initiated by the master device Other functions Transparent communication, via the master, with any device in an X-WAY architecture Diagnostics, debugging, adjustment and programming of PLCsSecurity Monitoring Check character on each frame, acknowledgement and repetition of messages, if required, ensures transmission security Bus status table, transmission error counters and device status can be accessed by program in each device Bus status and devices connected from the master PLC (except for TSX Nano) can be accessed from SYSDIAG software on an FTX 417/517 terminal or PC compatible (1)3 devices maximum with TSX Nano/Master PLC. (2) 5 datalink addresses with TSX Nano/Master PLC. Note : Some devices have application, network and datalink layers which are compatible with the UNI-TELWAY communication architecture, but do not have a standard physical interface (limited data rate, remote power supply, etc).

Performance
BCT (ms)

The UNI-TELWAY bus cycle time depends on the : ii i i Number of devices polled (datalink addresses) Data rate Turnaround time of each device Number, length and type of message

400

1
300

2
200

BCT = Bus Cycle Time, is the interval time between two polls to the same device.

100

1 = 9.6 K bits/s 2 = 19.2 K bits/s
1 4 8 12 16 20 24 27

The above curve gives the UNI-TELWAY cycle time as a function of the number of slaves at9.6 K bits/s or 19.2 K bits/s, with a typical turnaround time of 5 ms per device (excluding messages).

42702/2

Te

Bus and network modules
UNI-TELWAY bus Characteristics, devices which can be connected
References : pages 42702/6 and 42702/7 The following table shows the time to be added (in ms) to obtain the true BCT value as a function of the traffic (N = Number of usable characters) :Exchanges Master to slave Slave to master Time (ms) 9.6 K bits/s 24 + 1.2 N (1) 19 + 1.2 N (1) 19.2 K bits/s 17 + 0.6 N (1) 12 + 0.6 N (1)

Slave to slave 44 + 2.3 N (1) 29 + 1.15 N (1) (1) N = Number of usable characters corresponding to the messages to be exchanged. In a distributed control system architecture, the application-to-application response time not only depends on the communicationsystem, but also on : i The processing times of the message source and destination devices i The degree of asynchronism between the bus and processor cycle times This response time must be evaluated by the designer of each application according to the devices which are connected. The processing time of a device may vary from one to two cycle times depending on the degree of asynchronism.

EventDevice 1 CT1 TC1 BCT CT2 CT2

Confirmation CT1 CT1 BCT

UNI-TELWAY bus Device 2

BCT = UNI-TELWAY bus cycle time. CT1 = Device 1 bus cycle time.

Action

CT2 = Device 2 bus cycle time.

Devices which can be connected
TSX/PMX model 40 PLCs TSX/PMX PLCs can be connected to the UNI-TELWAY bus master or slave in a number of ways : 1 Via integral link The UNI-TELWAY bus and PLC processor...