The FTC470XDP protocol converter
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FTC470XDP_D00111_00_M_XXEN/02.2015
4.4 PROFIBUS DP side of the FTC470XDP
The FTC470XDP is a PROFIBUS DP slave in accordance with EN 50170. That means that at least one
Master must exist on the PROFIBUS side.
FTC470XDP = PROFIBUS DP slave
PROFIBUS DP address = 1…99
Data transmission rate = 9.6 kbit/s to 12 Mbit/s
Detection of the baud rate is carried out automatically.
4.4.1
Cyclical data exchange
In this manual, the PROFIBUS is generally regarded from the PROFIBUS DP Master’s point of view.
The communication process on the PROFIBUS DP is organized in cycles, which means that the PROFI-
BUS Master interrogates all PROFIBUS Slaves, one after the other. The Master sends a request to the
Slave, these represents the Master’s output data. In reply the FTC470XDP sends an answer, these are
the Master’s input data.
Due to the large amount of data on the BMS side, a cyclical data exchange is not possible at the same
time. For that reason, the PROFIBUS-DP Master must define the data he wants to receive from the
BMS device.
The allocation of input and output data is organized via a consecutive ID number. A request with the
ID number 1 must be followed by an answer from the Slave with the ID number 1. Only then the next
request with ID number 2 may be sent. Since one ID number needs 1 byte, the numbers from 0 to
255 can be allocated. Then it starts again with number 0.
4.4.2
Correct time control of the FTC470XDP by PROFIBUS commands is required
Since commands are intended for different devices, different time behaviour must be considered.
Answers to previously sent requests may accumulate while a PROFIBUS-DP Master’s request is being
answered by the associated Slave (FTC470XDP).Therefore it is of utmost importance to compare the
ID number of the request to the respective ID number of the answer.
Command
typ.
duration
max.
duration
BMS operation mode
Commands 1, 2, 3, 4, 102, 104, 105 execute
20 ms
100 ms
Slave, Master
Switching commands execute
160 ms
600 ms
Master, temporarily Master
Parameterizing
160 ms
600 ms
Master, temporarily Master
Taking over the master function
6 s
60 s
Slave
Returning the master function
100 ms
200 ms
temporarily Master
The PROFIBUS programmer is responsible for the correct increment of the ID
numbers in compliance the system requirements. Wrong control of the time
behaviour may result in misinterpretations (PROFIBUS input data)!
Consider the duration for the execution of the instructions!
