ProSoft Technology PTQ-PDPMV1 - Manual (Page 287)

PTQ-PDPMV1 ♦ Quantum Platform Reference
PROFIBUS DP Master Network Interface Module for Quantum User Manual
ProSoft Technology, Inc. Page 287 of 306
August 12, 2014
Backplane Loop 2
When the processor reaches end of scan (EOS), the processor provides an
interrupt to the PTQ. The PTQ locks out the processor and takes control of the
backplane for a period of time to transfer all input and output data described
above. After the data is transferred, the PTQ releases the backplane hook to the
processor, and the processor continues with the next scan. The process repeats
for every scan time. The time, T
BP
backplane transfer time, is nominally 7.0 ms
for a complete transfer of data. This is maximum time for all 1984 input bytes and
1838 output bytes (this includes cyclic, acyclic, mailbox command data, and input
output status data). The user is able to control the number of input and output
bytes within ProSoft Configuration Builder. The module supports 1536 bytes
input data and 1536 bytes output cyclic data.
PTQ-PDPMV1 Main Loop 3
The PTQ transfers the data from the backplane buffer to the PROFIBUS Master
buffer in preparation to condition the data for slave type data consistency. This
time, T
PTQ
, PTQ process time, is nominally 45 ms. During this loop, the PTQ
module alternatively locks the input and output data areas and exchanges the
data. It also transfers acyclic mailbox data.
PROFIBUS Loop 4
The PROFIBUS cycle time is based on many factors, including:
 synchronization time
 slave response time
 idle time
 bus baud rate
The cycle time "TMC" is calculated and added to processor scan time "T
PTQ
" and
"T
BP
" time to arrive at the maximum response time of the PROFIBUS system.