Bender ISOMETER iso1685FR, Руководство пользователя

Страница: 32 / 52

Device communication
32 iso1685FR(M)_D00002_02_M_XXEN/06.2017
6.1.2 Topology of the RS-485 network
The optimum topology for an RS-485 network is a daisy-chain connection. In this connection, device 1 is con-
nected to device 2, device 2 to device 3, device 3 to device n etc. The RS-485 network represents a continuous
path without branches.
Correct arrangement
Three examples for correct arrangement:
Wrong arrangement
Three examples for wrong arrangement
Wiring
The following type of wiring is recommended for the RS-485 network:
≥
Shielded cable, core diameter 0.8 (e.g. J-Y(St)Y 2x0.8), shield connected to earth (PE) at one end.
Connection to terminals A and B.
The number of bus nodes is restricted to 32 devices. If more devices are to be connected, Bender provides a DI-
1DL repeater.
6.1.3 BMS protocol
This protocol is an essential part of the Bender measuring device interface (BMS bus protocol). Data transmissi-
on generally makes use of ASCII characters.
Interface data are:
• Baud rate:9600 baud
• Transmission:1 start bit, 7 data bits, 1 parity bit, 1 stop bit (1, 7, E, 1)
• Parity:even
• Checksum:Sum of all transmitted bytes = 0 (without CR and LF)
The BMS bus protocol works according to the MASTER-SLAVE principle. Only one MASTER may exist in each net-
work. All bus devices are identified by a unique BMS address. The MASTER cyclically scans all other slaves on the
bus, listens to their signals and then carries out the corresponding commands.
A device receives the MASTER function when it is assigned bus address 1.
The ISOMETER® can only be operated as a BMS SLAVE!
DI1
1 32
33 64