HBM ML77B, Руководство по эксплуатации

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Introduction
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A00760_09_E00_00 HBM: public
ML77B
3 Introduction
The ML77B module uses the internal bus (link) to access measured values
from other system modules and “hand them over” to the Profibus. The Profibus
output (e.g. taring, zeroing, clearing peak value stores, predefining limit value
levels) is transmitted to the respective amplifiers via the internal serial interface
in the form of single commands.
The data contents for the Profibus is selected via the Profibus communication
telegram. The DP protocol is used on the Profibus.
The Profibus enables a maximum of 244 bytes of input and 244 bytes of output
data to be transmitted.
Transmission of:
- measured values (gross, net, peak, sample time)
- limit switch status
- control bits for taring, zeroing, peak value control, parameter set switch­
ing, and
- optionally, the limit value levels
- press-fit results
In general, only instantaneous values are available on the Profibus.
The update rates on the Profibus vary according to the Profibus master and the
Profibus baud rate (max. 12 Mbaud), data is read in at a rate of 2,400 Hz per
second via the link. If with large numbers of channels the CPU capacity is not
sufficient, it might prove necessary to reduce this rate. With 15 channels with
one signal each, an update rate of 1,200 Hz is achieved.
Notice
Please note that MGCplus measurement cycles are asynchronous to the Profi­
bus cycle. Hence, it is possible that not all values will reach the receiver at the
same time.