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VIPA System 300S
6.4.8.2
FC 02 - Read Input Status
Request message
ADDR
Reply message
ADDR
start_addr
HB130 | CP | 341-1CH01 | en | 18-40
n
Address calculation:
–
Byte address = ((start_addr - Param-start-address) / 8) + PLC-area
–
Rest-bit-number = (start_addr - Param-start-address) % 8 [Modulo 8]
start_addr
hex
decimal
0000h
0
0001h
1
01F1h
497
0400h
1024
0401h
1025
07DAh
2010
0800h
2048
0801h
2064
0C80h
3200
0FE0h
4064
0FF0h
4080
1000h
4096
This function enables the Modbus master to read individual bits from the input area of the
CPU.
FUNC
FUNC
n
The Modbus bit address start_addr contains the start of the area of the CPU, which is
be accessed.
n
The corresponding address allocation of the CPU memory area is established by the
properties of "FC 02" in the parameterization of the CP.
–
Here the "Modbus address in transmission message" briefly Param-start-address
may be assigned to a "SIMATIC memory area" briefly PLC-area.
Access
Calculation
Memory
(0 - 0)
Memory
(1 - 0)
Memory
(497 - 0)
Output
(1024 - 1024)
Output
(1025 - 1024)
Output
(2010 - 1024)
Timers
(2048 - 2048)
Timers
(2064 - 2048)
Timers
(3200 - 2048)
Counters (4064 - 4064)
Counters (4080 - 4064)
Counters (4096 - 4064)
start_addr
byte_count n
Communication protocols
Modbus > Modbus Slave - Function codes
/ 8
+1000
/ 8
+1000
/ 8
+1000
/ 8
+100
/ 8
+100
/ 8
+100
/ 16
+100
/ 16
+100
/ 16
+100
/ 16
+200
/ 16
+200
/ 16
+200
bit_number
n byte data
Area in
PLC
→
M 1000.0
→
M 1000.1
→
M 1062.1
→
Q 100.0
→
Q 100.1
→
Q 223.2
→
T 100
→
T 101
→
T 172
→
C 200
→
C 201
→
C 202
CRC
CRC
81
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