Dressler 13150 400 V, User Manual

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4-32 Communication Interfaces HPG 13150 400 V (A)
Dressler
®
HF-Technik GmbH
Prerelease version
You can create a work around to this problem with a command sequence. (For
more information about PROFIBUS commands, see “Host Port Commands”
on page 4-39 .) Here is an example procedure:
1. Send the null command (command 0 ). The HPG generator ignores this
command.
2. Update the download packet with data for the desired command.
3. Update the packet with the desired command.
4. Send the download packet.
5. Repeat step 1, and continue as needed.
By creating a procedure like this one, you can ensure the data for a command
will not be changed before the next download packet is received.
PROFIBUS Command Structure
The PROFIBUS is command-based. Dressler defines a download packet
(“outbytes”) and an upload packet (“inbytes”) as described in the following
sections of this chapter. Command lists follow.
Note: Response times are fast, so requested information is available in less
than 100 ms. More specifically, a download packet (“outbytes”) has high
priority for the PROFIBUS and is processed immediately. The upload
packet has lower priority and is updated every 100 ms, with the
exception of the “output on” status bit, which is updated every 20 ms.
PROFIBUS Download Packet
The download packet for the PROFIBUS contains four bytes, as shown in
Table 4-6 .
In the packet, bytes 1, 2, and 3 comprise the “data field” and contain
information defined by the command. Note that when the information extends
over more than one byte, the packet sends the least significant byte (LSB)
before the most significant byte (MSB).
Table 4-6. Configuration of download bytes (outbytes)
Byte Description
0 Command
1 Data byte (LSB)
2 Data byte
3 Data byte (MSB)