318
Manual – IPOSplus®
23
Communication commands
Assembler – Commands
Object structure
H+0
Object number (CAN-Bus-ID):
The object number is used for addressing the data object.
The object numbers of the sender (TRANSMIT) and receiver (RECEIVE) must be the same
for the data exchange.
H+1
Cycle time
in ms: Specifies the time interval after which the data is sent again.
Valid cycle times:
See _SbusCommDef (page 227)
Note:
The value 0 ms causes an error message to be issued in the return code.
The cycle time must always exceed the longest offset time.
H+2
Offset
in ms distributes the bus load when several SCOM TRANSMIT... commands are used.
514549899
Valid offset times:
See _SbusCommDef (page 227)
H+3
Number of data bytes and data format
Bit
Value
Function
0...3
0...8
Number of data bytes
4...7
0
Reserved
8
0...1
0 = MOTOROLA format
1 = INTEL format
The format of the sender and receiver must be
the same!
9...31
0
Reserved
H+4
Number of variable H" at which the data to be sent are to start.
H+5
Result (Return Code) of SCOM command
≥
0
Free bus capacity in % (calculated value of this unit)
-1
Incorrect cycle time
-2
Too many objects set up
-3
Bus overload
-5
Wrong object number
-6
Wrong length
Ensure that the entire calculated bus utilization does not exceed 70% for additional data
exchange between slaves.
The bus utilization is calculated in bits per second using the formula:
Number of telegrams × bits/telegram × 1/cycle time
For example, 2 messages with 100 bits in 1 ms cycle = 200000 bits/s = 200 kBaud
This results in the following bus load percentage in reference to the selected baud rate.
For example, 200 kBaud / 500 kBaud = 40% < 70%
t
t
cycle
t
offset
[
1
]
[
2
]
[
1
]
[
2
]
P
i
f
kVA
Hz
n
P
i
f
kVA
Hz
n