Bender FTC470XMB, Руководство по эксплуатации

Страница: 26 / 100

The FTC470XMB protocol converter
26 TGH1367en/06.2010
4.5.4 FTC470XMB communicate with the
Modbus RTU Master as "BMS Slave"
If a BMS address between 2 and 30 has been assigned to the FTC470XMB, it acts as a BMS
Slave. In this case, the Modbus RTU Master can use the following functions:
* For detailed information about the Modbus RTU instruction code refer to the tables „bus
requests“ beginning on page 34.
Taking over the Master function temporarily
Setting or requesting parameters of BMS cannot be carried out unless the FTC470XMB has
taken over the Master function on the BMS bus. After the setting respectively the requesting
of parameters, the Master function must be returned to the initial BMS Master. For the asso-
ciated commands refer to on page 43 and page 84.
If no parameters are transmitted to the BMS bus by the Modbus RTU for 200 seconds, the
FTC470XMB "assumes" that the Master function has not been returned. In this case, the
FTC470XMB automatically returns the Master function to the initial BMS Master in order to
avoid that the BMS bus is operated without a Master and hence would not be able to function
reliably.
The response time for taking over or returning the Master function depends on the extension
of the BMS system. A typical response time for taking over is approximately 6 seconds, but
may be up to 60 seconds in extended systems. The returning typical demands 100 ms, in
maximum up to 200 ms.
The time needed to execute the instruction codes 1, 2, 3, 4, 105, 102 and 104 is about 20 ms.
4.5.5 FTC470XMB communicates as the "BMS Master" with the
Modbus RTU Master
Once the BMS address 1 is assigned to the FTC470XMB, the device acts as the BMS Master.
In this way it can act as Master in all BMS systems. In addition to the interrogation of alarm
and operating messages, it is also possible to set switching commands and parameters.
The response time for the instruction codes 1, 2, 3, 4, 105, 102 and 104 is about 20 ms as it
is in the Slave mode. Switching commands and requesting of parameters are usually execut-
ed within approximately 160 ms. Depending on the size of the BMS systems, however, also
up to 600 ms are possible.
Function in the BMS network
Modbus RTU
instruction
code*
Request for the number of alarm messages of a device 1
Request for the alarm message of a channel 2
Request for the number of operating messages of a device 3
Request for the operating message of a channel 4
Request for the actual measuring value of a channel 105
Transmission of an alarm message from the Modbus RTU to a
channel of the FTC470XMB
102
Transmission of an operating message from the Modbus RTU
to a channel of the FTC470XMB
104
Starting, stopping or setting the position mode at EDS470/473
systems
115
Taking over respectively returning the Master function 112