ABB 07CR41 Operating Manual page 105

6.2.4 Response times for MODBUS
Advant Controller AC 31 / Issued: 01.99
Example of the use of the MODBUS
An example of the use of MODBUS
- A program is not required in the MODBUS
- Example of a program in the MODBUS
Read the 6 bits E62,00 to E62,05 in the MODBUS
The information is written to A62,00 to A62,05 of the AC31 MODBUS
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The MODBUS address of variable E62,00 in slave 1 is 992 as a decimal value.
M0,0
KW1,0 =
KW1,1 =
KW1,2 =
KW1,3 = 992
KW1,4 =
AW62,00
A delay should be programmed so that the MODBUS
of an error. This delay is called TIME_OUT and is usually 2 seconds.
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communication
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The MODBUS processing time depends on the following factors:
- Baud rate
- Number of frame bytes
- Basic unit cycle time
- Basic unit load factor
The following times are only given as guidelines.
Response times for a 40 or 50 series basic unit
Cycle time = 10 ms
Load factor = 80%
Baud rate = 9,600 baud
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function
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communication between two 40 series basic units.
40 series
MODBUS
master
MODBUS protocol
RS-232 line
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slave basic unit.
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master basic unit:
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slave 1 basic unit .
MODBUS
FREI
1
SLAV
2
FCT
2
TIME
ADDR RDY
6
NB ERR
DATA ERN
6 – 11 Communication
40 series
MODBUS
slave 1
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master basic unit.
M0,0
M0,1
MW0,0
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message can be sent again in the event
3