HIMA HIQuad X - Maximum Communication Time Slice

Programming System
Page 74 of 110 HI 803 211 E Rev. 1.01.00
6.1.3.3 Maximum Communication Time Slice
The maximum communication time slice is the time period in milliseconds (ms) per CPU cycle
assigned to the processor module for processing the communication tasks. Even if the protocol
processing could not be completed within one communication time slice, the CPU still executes
the safety-relevant monitoring for all protocols within one CPU cycle.
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If not all upcoming communication tasks can be processed within one CPU cycle, the whole
communication data is transferred over multiple CPU cycles. The number of communication
time slices is then greater than 1.
For calculating the maximum response time, the number of communication time slices must be
equal to 1.
Determining the Maximum Duration of the Communication Time Slice
For a first estimate of the maximum duration of the communication time slice for the HIQuad X
system, the sum of the following times must be entered in the Max. Com. Time Slice [ms]
system parameter located in the properties of the resource:
 For each F-COM module: 3 ms.
 For each redundant safeethernet connection: 1 ms.
 For each non-redundant safeethernet connection: 0.5 ms.
 For each kilobyte user data of non-safety-related protocols, e.g., Modbus: 1 ms.
HIMA recommends comparing the value estimated for Max. Com. Time Slice [ms] with the value
displayed in the Control Panel and, if necessary, correcting it in the properties of the resource.
This can be done during an FAT (factory acceptance test) or SAT (site acceptance test).
To determine the actual duration of the maximum communication time slice
1. Operate the HIQuad X system under full load (FAT, SAT):
All communication protocols are in operation (safeethernet and standard protocols).
2. Open the Control Panel and select the Com. Time Slice structure tree folder.
3. Read the vale displayed for Maximum Com. Time Slice Duration per Cycle [ms].
4. Read the value displayed for Maximum Number of Required Com. Time Slice Cycles.
The duration of the communication time slice must be set so that, when using the
communication time slice, the CPU cycle cannot exceed the watchdog time specified by the
process.