RSTi-OM User Manual
Section 11
GFK-3212A
Jun 2021
Modbus/TCP Interface
110
11.1
Modbus Function Codes
This table shows the supported Modbus function codes.
Message Type
Function Code
Maximum Message Size
Read Holding Registers
3
250 Bytes (125 Words)
Write Single Register
6
2 bytes (1 Word)
Write Multiple Registers
16 (10 hex)
246 Bytes (123 Words)
Read/Write Holding Registers
23 (17 hex)
Write: 242 bytes (121 Words
Read: 246 bytes (123 Words)
11.2
Modbus Address Definitions
The address definitions for the Modbus/TCP interface are shown in the following tables.
IO-Link Port 1
IO-Link Port 2
IO-Link Port 3
IO-Link Port 4
Access
Length
Multiple
Port PDI
Data
Block(s)
999 (Base 0)
1000 (Base 1)
1999 (Base 0)
2000 (Base 1)
2999 (Base 0)
3000 (Base 1)
3999 (Base 0)
4000 (Base 1)
Read-
Only
Configurable
per port (s)
Port
Specific
PDI Data
Block
1000 (Base 0)
1001 (Base 1)
2000 (Base 0)
2001 (Base 1)
3000 (Base 0)
3001 (Base 1)
4000 (Base 0)
4001 (Base 1)
Read-
Only
Configurable
per port
Multiple
Port PDO
Data
Block(s)
1049 (Base 0)
1050 (Base 1)
2049 (Base 0)
2050 (Base 1)
3049 (Base 0)
3050 (Base 1)
4049 (Base 0)
4050 (Base 1)
Read/
Write
Configurable
per port(s)
Port
Specific
PDO Data
Block
1050 (Base 0)
1051 (Base 1)
2050 (Base 0)
2051 (Base 1)
3050 (Base 0)
3051 (Base 1)
4050 (Base 0)
4051 (Base 1)
Read/
Write
Configurable
per port
Receive
ISDU
Response
1100 (Base 0)
1101 (Base 1)
2100 (Base 0)
2101 (Base 1)
3100 (Base 0)
3101 (Base 1)
4100 (Base 0)
4101 (Base 1)
Read-
Only
4 to 125
Words
Transmit
ISDU
Request
1300 (Base 0)
1301 (Base 1)
2300 (Base 0)
2301 (Base 1)
3300 (Base 0)
3301 (Base 1)
4300 (Base 0)
4301 (Base 1)
Write-
Only
4 to 123
Words
Port Information Block (Continuous Block)
232 Words
Vendor
Name
1500 (Base 0)
1501 (Base 1)
2500 (Base 0)
2501 (Base 1)
3500 (Base 0)
3501 (Base 1)
4500 (Base 0)
4501 (Base 1)
Read-
Only
64 Chars
32 Words
Vendor
Text
1532 (Base 0)
1533 (Base 1)
2532 (Base 0)
2533 (Base 1)
3532 (Base 0)
3533 (Base 1)
4532 (Base 0)
4533 (Base 1)
Read-
Only
64 Chars
32 Words
Product
Name
1564 (Base 0)
1565 (Base 1)
2564 (Base 0)
2565 (Base 1)
3564 (Base 0)
3565 (Base 1)
4564 (Base 0)
4565 (Base 1)
Read-
Only
64 Chars
32 Words