Bender ISOMETER isoPV1685RTU, Руководство пользователя, Страница: 26 / 36

Device communication Device communication
isoPV1685xxx_D00007_05_M_XXEN/02.2020
26
8.5 Modbus RTU (isoPV1685RTU)
The Modbus RTU is used for integration of Bender devices featuring a Modbus RTU inter-
face into systems with a Condition Monitor (e.g. CP700, COM465xP) or for integration into
third-party systems.
The Modbus RTU transmits measured values, status messages, control commands or de-
vice parameters as binary codes.
For more detailed information regarding Modbus RTU including features and commis-
sioning, refer to the "Modbus RTU" manual at
http://www.bender.de/manuals .
8.5.1 Switching between BMS and Modbus
Use switch 1 of the DIP switch SS8103 to switch between communication with BMS or
Modbus.
8.5.2 Commissioning RS-485 network with Modbus protocol
In order to enable communication of devices via Modbus RTU, they have to be connected
to the same bus. The Modbus interface of the isoPV1685RTU uses the same physical in-
terface as the BMS bus: the RS-485 interface.
• Interconnect terminals A and B (see "Connections" on page 13 ) of all bus devices in
one line.
• Switch the terminating resistors on at the start and the end of the RS-485 network. If
a device at the end of the bus is not terminated, connect a 120 Ω resistor to termi-
nals A and B
• Switch the supply voltage on
• Assign master function and address 1 to a device
• Assign addresses (2...17) to all other bus devices in consecutive order
Switch 1
SS8103
Protocol
OFF
(switch position
up) BMS
ON
(switch position
down) Modbus RTU
SS8103
1
2
3
4
5
6
7
8
A4
A3
A2
A1
A0
8.5.3 Setting Modbus address
Set the Modbus address by means of switches 2 to 5 of the DIP switch SS8103.
8.5.4 Modbus protocol settings
The following parameters are factory set and cannot be changed:
Data bits: 8 | Parity: None | Stopbits: 1
The baud rate can be changed via Modbus (register 0x3007).
The standard baud rate is 9600 baud. The following baud rates can be set:
• 9600 baud
• 19200 baud
• 38400 baud
• 57600 baud
8.5.5 Scanning cycle
Due to the low update rate, the scanning cycle for all Modbus registers should be ≥2 s.
The update rate for the measured values "insulation resistance" depends on the system
leakage capacitance of the PV system. The shortest update rate is approx. 5 s. The normal
update rate is > 10 s.
Switch position Value
OFF Switch position
up 0
ON Switch position
down 1
DIP switch SS8103 Modbus
address
2=A3 3=A2 4=A1 5=A0
0 0 0 0 2
0 0 0 1 3
0 0 1 0 4
0 0 1 1 5
0 1 0 0 6
0 1 0 1 7
0 1 1 0 8
… … … …
… … … …
1 1 1 1 17
SS8103
1
2
3
4
5
6
7
8
A4
A3
A2
A1
A0