MODBUS

MODBUS Protocol

Modicon Communication Bus (MODBUS) is an application layer protocol for client-server communication between a switch (server) and a device in the network running MODBUS client software (client). You can use MODBUS over a serial line to connect a computer to a remote terminal unit (RTU) in supervisory control and data acquisition (SCADA) systems.

MODBUS also runs on Ethernet TCP/IP networks. Use MODBUS TCP over an Ethernet network when connecting the switch to devices such as intelligent electronic devices (IEDs), distributed controllers, substation routers, IP phones, Wireless Access Points, and other network devices such as redundant substation switches.

The client can be an IED or a human machine interface (HMI) application that remotely configures and manages devices running MODBUS TCP. The switch functions as the server.

The switch encapsulates a request or response message in a MODBUS TCP application data unit (ADU). A client sends a message to a TCP port on the switch.

MODBUS TCP Registers

This document lists the read-only registers for switches. MODBUS clients use them to communicate with a MODBUS server (the switch). There are no writable registers.

System Information Registers

Address spaces 0x0800 through 0x0FFF are system information read-only registers. These 2048 registers are accessible by MODBUS function code 0x03 Read Multiple Registers.

Table 1. System Information Registers
Address Number of Registers Description R/W Format

Value

0x0800

64

Product ID

R

Text

0x0840

64

Software image name

R

Text

0x0880

64

Software image version

R

Text

0x08C0

64

Host Name

R

Text

0x0900

1

Number of Gigabit Ethernet ports

R

Uint 16

0x0901

1

Number of 10 Gigabit Ethernet ports

R

Uint 16

0x0902

1

Number of mgig Ethernet ports

R

Uint 16

0x0903

1

Number of power supplies

R

Uint 16

0x0904

1

Power supply 1 status

R

Uint 16

0 – Not present

1 – Present

0x0905

1

Power supply 2 status

R

Uint 16

0 – Not present

1 – Present

0x0906

1

System or sensor ID 0 temperature

R

Uint 16

0x0907

1

Alarm 1 – Description

R

Uint 16

0x0947

2

Alarm 2 Description

R

Uint 16

0x0987

1

Number of Alarms

R

Uint 16

0x0988

1

Alarm 1 Status

R

Uint 16

0 – Alarm off

1 – Alarm on

0x0989

2

Alarm 2 Status

R

Uint 16

0 – Alarm off

1 – Alarm on

0x098A

64

Alarm 3 Description

R

Text

0x09CA

64

Alarm 4 Description

R

Text

0x0A0A

1

Alarm 3 Status

R

Uint16

0 – Alarm off

1 – Alarm on

0x0A0B

1

Alarm 4 Status

R

Uint16

0 – Alarm off

1 – Alarm on

Port Information Registers

Address spaces 0x1000 through 0x3FFF are port information read-only registers. These 12,000 registers are accessible by MODBUS function code 0x03 Read Multiple Registers. They are updated every time upon receiving a read request to the register(s).

The following table shows the memory map for all interface registers, with 64-bit counters (Address space 0x1000 through 0x2FFF, 8,000 registers).

Table 2. 11 Port Registers

Address

Number of Registers

Description

R/W

Format

1000

64

Port 1 Name

R

Text

1040

64

Port 2 Name

R

Text

1080

64

Port 3 Name

R

Text

10C0

64

Port 4 Name

R

Text

1100

64

Port 5 Name

R

Text

1140

64

Port 6 Name

R

Text

1180

64

Port 7 Name

R

Text

11C0

64

Port 8 Name

R

Text

1200

64

Port 9 Name

R

Text

1240

64

Port 10 Name

R

Text

1280

64

Port 11 Name

R

Text

12C0

1

Port 1 State

R

Uint16

12C1

1

Port 2 State

R

Uint16

12C2

1

Port 3 State

R

Uint16

12C3

1

Port 4 State

R

Uint16

12C4

1

Port 5 State

R

Uint16

12C5

1

Port 6 State

R

Uint16

12C6

1

Port 7 State

R

Uint16

12C7

1

Port 8 State

R

Uint16

12C8

1

Port 9 State

R

Uint16

12C9

1

Port 10 State

R

Uint16

12CA

1

Port 11 State

R

Uint16

12CB

4

Port 1 Statistics – Number of packets received

R

Uint64

12CF

4

Port 2 Statistics – Number of packets received

R

Uint64

12D3

4

Port 3 Statistics – Number of packets received

R

Uint64

12D7

4

Port 4 Statistics – Number of packets received

R

Uint64

12DB

4

Port 5 Statistics – Number of packets received

R

Uint64

12DF

4

Port 6 Statistics – Number of packets received

R

Uint64

12E3

4

Port 7 Statistics – Number of packets received

R

Uint64

12E7

4

Port 8 Statistics – Number of packets received

R

Uint64

12EB

4

Port 9 Statistics – Number of packets received

R

Uint64

12EF

4

Port 10 Statistics – Number of packets received

R

Uint64

12F3

4

Port 11 Statistics – Number of packets received

R

Uint64

12F7

4

Port 1 Statistics – Number of packets sent

R

Uint64

12FB

4

Port 2 Statistics – Number of packets sent

R

Uint64

12FF

4

Port 3 Statistics – Number of packets sent

R

Uint64

1303

4

Port 4 Statistics – Number of packets sent

R

Uint64

1307

4

Port 5 Statistics – Number of packets sent

R

Uint64

130B

4

Port 6 Statistics – Number of packets sent

R

Uint64

130F

4

Port 7 Statistics – Number of packets sent

R

Uint64

1313

4

Port 8 Statistics – Number of packets sent

R

Uint64

1317

4

Port 9 Statistics – Number of packets sent

R

Uint64

131B

4

Port 10 Statistics – Number of packets sent

R

Uint64

131F

4

Port 11 Statistics – Number of packets sent

R

Uint64

1323

4

Port 1 Statistics – Number of packets received

R

Uint64

1327

4

Port 2 Statistics – Number of packets received

R

Uint64

132B

4

Port 3 Statistics – Number of packets received

R

Uint64

132F

4

Port 4 Statistics – Number of packets received

R

Uint64

1333

4

Port 5 Statistics – Number of packets received

R

Uint64

1337

4

Port 6 Statistics – Number of packets received

R

Uint64

133B

4

Port 7 Statistics – Number of packets received

R

Uint64

133F

4

Port 8 Statistics – Number of packets received

R

Uint64

1343

4

Port 9 Statistics – Number of packets received

R

Uint64

1347

4

Port 10 Statistics – Number of packets received

R

Uint64

134B

4

Port 11 Statistics – Number of packets received

R

Uint64

134F

1

Port 1 Statistics – Number of bytes sent

R

Uint64

1353

1

Port 2 Statistics – Number of bytes sent

R

Uint64

1357

1

Port 3 Statistics – Number of bytes sent

R

Uint64

135B

1

Port 4 Statistics – Number of bytes sent

R

Uint64

135F

1

Port 5 Statistics – Number of bytes sent

R

Uint64

1363

1

Port 6 Statistics – Number of bytes sent

R

Uint64

1367

1

Port 7 Statistics – Number of bytes sent

R

Uint64

136B

1

Port 8 Statistics – Number of bytes sent

R

Uint64

136F

1

Port 9 Statistics – Number of bytes sent

R

Uint64

1373

1

Port 10 Statistics – Number of bytes sent

R

Uint64

1377

1

Port 11 Statistics – Number of bytes sent

R

Uint64
Table 3. Values for Getting 15 Port Registers

Address

Number of Registers

Description

R/W

Format

1000

64

Port 1 Name

R

Text

1040

64

Port 2 Name

R

Text

1080

64

Port 3 Name

R

Text

10C0

64

Port 4 Name

R

Text

1100

64

Port 5 Name

R

Text

1140

64

Port 6 Name

R

Text

1180

64

Port 7 Name

R

Text

11C0

64

Port 8 Name

R

Text

1200

64

Port 9 Name

R

Text

1240

64

Port 10 Name

R

Text

1280

64

Port 11 Name

R

Text

12C0

64

Port 12 Name

R

Text

1300

64

Port 13 Name

R

Text

1340

64

Port 14 Name

R

Text

1380

64

Port 15 Name

R

Text

13C0

1

Port 1 Status

R

Text

13C1

1

Port 2 Status

R

Text

13C2

1

Port 3 Status

R

Text

13C3

1

Port 4 Status

R

Text

13C4

1

Port 5 Status

R

Uint16

13C5

1

Port 6 Status

R

Uint16

13C6

1

Port 7 Status

R

Uint16

13C7

1

Port 8 Status

R

Uint16

13C8

1

Port 9 Status

R

Uint16

13C9

1

Port 10 Status

R

Uint16

13CA

1

Port 11 Status

R

Uint16

13CB

1

Port 12 Status

R

Uint16

13CC

1

Port 13 Status

R

Uint16

13CD

1

Port 14 State

R

Uint16

13CE

1

Port 15 State

R

Uint16

13CF

4

Port 1 Statistics – Number of packets received

R

Uint16

13D3

4

Port 2 Statistics – Number of packets received

R

Uint16

13D7

4

Port 3 Statistics – Number of packets received

R

Uint16

13DB

4

Port 4 Statistics – Number of packets received

R

Uint16

13DF

4

Port 5 Statistics – Number of packets received

R

Uint16

13E 3

4

Port 6 Statistics – Number of packets received

R

Uint16

13E 7

4

Port 7 Statistics – Number of packets received

R

Uint16

13E B

4

Port 8 Statistics – Number of packets received

R

Uint16

13E F

4

Port 9 Statistics – Number of packets received

R

Uint64

13F3

4

Port 10 Statistics – Number of packets received

R

Uint64

13F7

4

Port 11 Statistics – Number of packets received

R

Uint64

13FB

4

Port 12 Statistics – Number of packets received

R

Uint64

13FF

4

Port 13 Statistics – Number of packets received

R

Uint64

1403

4

Port 14 Statistics – Number of packets received

R

Uint64

1407

4

Port 15 Statistics – Number of packets received

R

Uint64

140B

4

Port 1 Statistics – Number of packets sent

R

Uint64

140F

4

Port 2 Statistics – Number of packets sent

R

Uint64

1413

4

Port 3 Statistics – Number of packets sent

R

Uint64

1417

4

Port 4 Statistics – Number of packets sent

R

Uint64

141B

4

Port 5 Statistics – Number of packets sent

R

Uint64

141F

4

Port 6 Statistics – Number of packets sent

R

Uint64

1423

4

Port 7 Statistics – Number of packets sent

R

Uint64

1427

4

Port 8 Statistics – Number of packets sent

R

Uint64

142B

4

Port 9 Statistics – Number of packets sent

R

Uint64

142F

4

Port 10 Statistics – Number of packets sent

R

Uint64

1433

4

Port 11 Statistics – Number of packets sent

R

Uint64

1437

4

Port 12 Statistics – Number of packets sent

R

Uint64

143B

4

Port 13 Statistics – Number of packets sent

R

Uint64

143F

4

Port 14 Statistics – Number of packets sent

R

Uint64

1443

4

Port 15 Statistics – Number of packets sent

R

Uint64

1447

4

Port 1 Statistics – Number of bytes received

R

Uint64

144B

4

Port 2 Statistics – Number of bytes received

R

Uint64

144F

4

Port 3 Statistics – Number of bytes received

R

Uint64

1453

4

Port 4 Statistics – Number of bytes received

R

Uint64

1457

4

Port 5 Statistics – Number of bytes received

R

Uint64

145B

4

Port 6 Statistics – Number of bytes received

R

Uint64

145F

4

Port 7 Statistics – Number of bytes received

R

Uint64

1463

4

Port 8 Statistics – Number of bytes received

R

Uint64

1467

4

Port 9 Statistics – Number of bytes received

R

Uint64

146B

4

Port 10 Statistics – Number of bytes received

R

Uint64

146F

4

Port 11 Statistics – Number of bytes received

R

Uint64

1473

4

Port 12 Statistics – Number of bytes received

R

Uint64

1477

4

Port 13 Statistics – Number of bytes received

R

Uint64

147B

4

Port 14 Statistics – Number of bytes received

R

Uint64

147F

4

Port 15 Statistics – Number of bytes received

R

Uint64

1483

4

Port 1 Statistics – Number of bytes sent

R

Uint64

1487

4

Port 2 Statistics – Number of bytes sent

R

Uint64

148B

4

Port 3 Statistics – Number of bytes sent

R

Uint64

148F

4

Port 4 Statistics – Number of bytes sent

R

Uint64

1493

4

Port 5 Statistics – Number of bytes sent

R

Uint64

1497

4

Port 6 Statistics – Number of bytes sent

R

Uint64

149B

4

Port 7 Statistics – Number of bytes sent

R

Uint64

149F

4

Port 8 Statistics – Number of bytes sent

R

Uint64

14A3

4

Port 9 Statistics – Number of bytes sent

R

Uint64

14A7

4

Port 10 Statistics – Number of bytes sent

R

Uint64

14AB

4

Port 11 Statistics – Number of bytes sent

R

Uint64

14AF

4

Port 12 Statistics – Number of bytes sent

R

Uint64

14B3

4

Port 13 Statistics – Number of bytes sent

R

Uint64

14B7

4

Port 14 Statistics – Number of bytes sent

R

Uint64

14BB

4

Port 15 Statistics – Number of bytes sent

R

Uint64
Table 4. Values for Getting 19 Port Information

Address

Number of Registers

Description

R/W

Format

1000

64

Port 1 Name

R

Text

1040

64

Port 2 Name

R

Text

1080

64

Port 3 Name

R

Text

10C0

64

Port 4 Name

R

Text

1100

64

Port 5 Name

R

Text

1140

64

Port 6 Name

R

Text

1180

64

Port 7 Name

R

Text

11C0

64

Port 8 Name

R

Text

1200

64

Port 9 Name

R

Text

1240

64

Port 10 Name

R

Text

1280

64

Port 11 Name

R

Text

12C0

64

Port 12 Name

R

Text

1300

64

Port 13 Name

R

Text

1340

64

Port 14 Name

R

Text

1380

64

Port 15 Name

R

Text

13C0

64

Port 16 Name

R

Text

1400

64

Port 17 Name

R

Text

1440

64

Port 18 Name

R

Text

1480

64

Port 19 Name

R

Text

14C0

1

Port 1 State

R

Uint16

14C1

1

Port 2 State

R

Uint16

14C2

1

Port 3 State

R

Uint16

14C3

1

Port 4 State

R

Uint16

14C4

1

Port 5 State

R

Uint16

14C5

1

Port 6 State

R

Uint16

14C6

1

Port 7 State

R

Uint16

14C7

1

Port 8 State

R

Uint16

14C8

1

Port 9 State

R

Uint16

14C9

1

Port 10 State

R

Uint16

14CA

1

Port 11 State

R

Uint16

14CB

1

Port 12 State

R

Uint16

14CC

1

Port 13 State

R

Uint16

14CD

1

Port 14 State

R

Uint16

14CE

1

Port 15 State

R

Uint16

14CF

1

Port 16 State

R

Uint16

14D0

1

Port 17 State

R

Uint16

14D1

1

Port 18 State

R

Uint16

14D2

1

Port 19 State

R

Uint16

14D3

4

Port 1 Statistics – Number of packets received

R

Uint64

14D7

4

Port 2 Statistics – Number of packets received

R

Uint64

14DB

4

Port 3 Statistics – Number of packets received

R

Uint64

14DF

4

Port 4 Statistics – Number of packets received

R

Uint64

14E3

4

Port 5 Statistics – Number of packets received

R

Uint64

14E7

4

Port 6 Statistics – Number of packets received

R

Uint64

14EB

4

Port 7 Statistics – Number of packets received

R

Uint64

14EF

4

Port 8 Statistics – Number of packets received

R

Uint64

14F3

4

Port 9 Statistics – Number of packets received

R

Uint64

14F7

4

Port 10 Statistics – Number of packets received

R

Uint64

14FB

4

Port 11 Statistics – Number of packets received

R

Uint64

14FF

4

Port 12 Statistics – Number of packets received

R

Uint64

1503

4

Port 13 Statistics – Number of packets received

R

Uint64

1507

4

Port 14 Statistics – Number of packets received

R

Uint64

150B

4

Port 15 Statistics – Number of packets received

R

Uint64

150F

4

Port 16 Statistics – Number of packets received

R

Uint64

1513

4

Port 17 Statistics – Number of packets received

R

Uint64

1517

4

Port 18 Statistics – Number of packets received

R

Uint64

151B

4

Port 19 Statistics – Number of packets received

R

Uint64

151F

4

Port 1 Statistics – Number of packets sent

R

Uint64

1523

4

Port 2 Statistics – Number of packets sent

R

Uint64

1527

4

Port 3 Statistics – Number of packets sent

R

Uint64

152B

4

Port 4 Statistics – Number of packets sent

R

Uint64

152F

4

Port 5 Statistics – Number of packets sent

R

Uint64

1533

4

Port 6 Statistics – Number of packets sent

R

Uint64

1537

4

Port 7 Statistics – Number of packets sent

R

Uint64

153B

4

Port 8 Statistics – Number of packets sent

R

Uint64

153F

4

Port 9 Statistics – Number of packets sent

R

Uint64

1543

4

Port 10 Statistics – Number of packets sent

R

Uint64

1547

4

Port 11 Statistics – Number of packets sent

R

Uint64

154B

4

Port 12 Statistics – Number of packets sent

R

Uint64

154F

4

Port 13 Statistics – Number of packets sent

R

Uint64

1553

4

Port 14 Statistics – Number of packets sent

R

Uint64

1557

4

Port 15 Statistics – Number of packets sent

R

Uint64

155B

4

Port 16 Statistics – Number of packets sent

R

Uint64

155F

4

Port 17 Statistics – Number of packets sent

R

Uint64

1563

4

Port 18 Statistics – Number of packets sent

R

Uint64

1567

4

Port 19 Statistics – Number of packets sent

R

Uint64

156B

4

Port 1 Statistics – Number of bytes received

R

Uint64

156F

4

Port 2 Statistics – Number of bytes received

R

Uint64

1573

4

Port 3 Statistics – Number of bytes received

R

Uint64

1577

4

Port 4 Statistics – Number of bytes received

R

Uint64

157B

4

Port 5 Statistics – Number of bytes received

R

Uint64

157F

4

Port 6 Statistics – Number of bytes received

R

Uint64

1583

4

Port 7 Statistics – Number of bytes received

R

Uint64

1587

4

Port 8 Statistics – Number of bytes received

R

Uint64

158B

4

Port 9 Statistics – Number of bytes received

R

Uint64

158F

4

Port 10 Statistics – Number of bytes received

R

Uint64

1593

4

Port 11 Statistics – Number of bytes received

R

Uint64

1597

4

Port 12 Statistics – Number of bytes received

R

Uint64

159B

4

Port 13 Statistics – Number of bytes received

R

Uint64

159F

4

Port 14 Statistics – Number of bytes received

R

Uint64

15A3

4

Port 15 Statistics – Number of bytes received

R

Uint64

15A7

4

Port 16 Statistics – Number of bytes received

R

Uint64

15AB

4

Port 17 Statistics – Number of bytes received

R

Uint64

15AF

4

Port 18 Statistics – Number of bytes received

R

Uint64

15B3

4

Port 19 Statistics – Number of bytes received

R

Uint64

15B7

4

Port 1 Statistics – Number of bytes sent

R

Uint64

15BB

4

Port 2 Statistics – Number of bytes sent

R

Uint64

15BF

4

Port 3 Statistics – Number of bytes sent

R

Uint64

15C3

4

Port 4 Statistics – Number of bytes sent

R

Uint64

15C7

4

Port 5 Statistics – Number of bytes sent

R

Uint64

15CB

4

Port 6 Statistics – Number of bytes sent

R

Uint64
15CF 4

Port 7 Statistics – Number of bytes sent

R

Uint64

15D3

4

Port 8 Statistics – Number of bytes sent

R

Uint64

15D7

4

Port 9 Statistics – Number of bytes sent

R

Uint64

15DB

4

Port 10 Statistics – Number of bytes sent

R

Uint64

15DF

4

Port 11 Statistics – Number of bytes sent

R

Uint64

15E3

4

Port 12 Statistics – Number of bytes sent

R

Uint64

15E7

4

Port 13 Statistics – Number of bytes sent

R

Uint64

15EB

4

Port 14 Statistics – Number of bytes sent

R

Uint64

15EF

4

Port 15 Statistics – Number of bytes sent

R

Uint64

15F3

4

Port 16 Statistics – Number of bytes sent

R

Uint64

15F7

4

Port 17 Statistics – Number of bytes sent

R

Uint64

15FB

4

Port 18 Statistics – Number of bytes sent

R

Uint64
Table 5. Values for Getting Port 27 Information

Address

Number of Registers

Description

R/W

Format

1000

64

Port 1 Name

R

Text

1040

64

Port 2 Name

R

Text

1080

64

Port 3 Name

R

Text

10C0

64

Port 4 Name

R

Text

1100

64

Port 5 Name

R

Text

1140

64

Port 6 Name

R

Text

1180

64

Port 7 Name

R

Text

11C0

64

Port 8 Name

R

Text

1200

64

Port 9 Name

R

Text

1240

64

Port 10 Name

R

Text

1280

64

Port 11 Name

R

Text

12C0

64

Port 12 Name

R

Text

1300

64

Port 13 Name

R

Text

1340

64

Port 14 Name

R

Text

1380

64

Port 15 Name

R

Text

13C0

64

Port 16 Name

R

Text

1400

64

Port 17 Name

R

Text

1440

64

Port 18 Name

R

Text

1480

64

Port 19 Name

R

Text

14C0

64

Port 20 Name

R

Text

1500

64

Port 21 Name

R

Text

1540

64

Port 22 Name

R

Text

1580

64

Port 23 Name

R

Text

15C0

64

Port 24 Name

R

Text

1600

64

Port 25 Name

R

Text

1640

64

Port 26 Name

R

Text

1680

64

Port 27 Name

R

Text

16C0

1

Port 1 State

R

Uint16

16C1

1

Port 2 State

R

Uint16

16C2

1

Port 3 State

R

Uint16

16C3

1

Port 4 State

R

Uint16

16C4

1

Port 5 State

R

Uint16

16C5

1

Port 6 State

R

Uint16

16C6

1

Port 7 State

R

Uint16

16C7

1

Port 8 State

R

Uint16

16C8

1

Port 9 State

R

Uint16

16C9

1

Port 10 State

R

Uint16

16CA

1

Port 11 State

R

Uint16

16CB

1

Port 12 State

R

Uint16

16CC

1

Port 13 State

R

Uint16

16CD

1

Port 14 State

R

Uint16

16CE

1

Port 15 State

R

Uint16

16CF

1

Port 16 State

R

Uint16

16D0

1

Port 17 State

R

Uint16

16D1

1

Port 18 State

R

Uint16

16D2

1

Port 19 State

R

Uint16

16D3

1

Port 20 State

R

Uint16

16D4

1

Port 21 State

R

Uint16

16D5

1

Port 22 State

R

Uint16

16D6

1

Port 23 State

R

Uint16

16D7

1

Port 24 State

R

Uint16

16D8

1

Port 25 State

R

Uint16

16D9

1

Port 26 State

R

Uint16

16DA

1

Port 27 State

R

Uint16

16DB

4

Port 1 Statistics – Number of packets received

R

Uint64

16DF

4

Port 2 Statistics – Number of packets received

R

Uint64

16E3

4

Port 3 Statistics – Number of packets received

R

Uint64

16E7

4

Port 4 Statistics – Number of packets received

R

Uint64

16EB

4

Port 5 Statistics – Number of packets received

R

Uint64

16EF

4

Port 6 Statistics – Number of packets received

R

Uint64

16F3

4

Port 7 Statistics – Number of packets received

R

Uint64

16F7

4

Port 8 Statistics – Number of packets received

R

Uint64

16FB

4

Port 9 Statistics – Number of packets received

R

Uint64

16FF

4

Port 10 Statistics – Number of packets received

R

Uint64

1703

4

Port 11 Statistics – Number of packets received

R

Uint64

1707

4

Port 12 Statistics – Number of packets received

R

Uint64

170B

4

Port 13 Statistics – Number of packets received

R

Uint64

170F

4

Port 14 Statistics – Number of packets received

R

Uint64

1713

4

Port 15 Statistics – Number of packets received

R

Uint64

1717

4

Port 16 Statistics – Number of packets received

R

Uint64

171B

4

Port 17 Statistics – Number of packets received

R

Uint64

171F

4

Port 18 Statistics – Number of packets received

R

Uint64

1723

4

Port 19 Statistics – Number of packets received

R

Uint64

1727

4

Port 20 Statistics – Number of packets received

R

Uint64

172B

4

Port 21 Statistics – Number of packets received

R

Uint64

172F

4

Port 22 Statistics – Number of packets received

R

Uint64

1733

4

Port 23 Statistics – Number of packets received

R

Uint64

1737

4

Port 24 Statistics – Number of packets received

R

Uint64

173B

4

Port 25 Statistics – Number of packets received

R

Uint64

173F

4

Port 26 Statistics – Number of packets received

R

Uint64

1743

4

Port 27 Statistics – Number of packets received

R

Uint64

1747

4

Port 1 Statistics – Number of packets sent

R

Uint64

174B

4

Port 2 Statistics – Number of packets sent

R

Uint64

174F

4

Port 3 Statistics – Number of packets sent

R

Uint64

1753

4

Port 4 Statistics – Number of packets sent

R

Uint64

1757

4

Port 5 Statistics – Number of packets sent

R

Uint64

175B

4

Port 6 Statistics – Number of packets sent

R

Uint64

175F

4

Port 7 Statistics – Number of packets sent

R

Uint64

1763

4

Port 8 Statistics – Number of packets sent

R

Uint64

1767

4

Port 9 Statistics – Number of packets sent

R

Uint64

176B

4

Port 10 Statistics – Number of packets sent

R

Uint64

176F

4

Port 11 Statistics – Number of packets sent

R

Uint64

1773

4

Port 12 Statistics – Number of packets sent

R

Uint64

1777

4

Port 13 Statistics – Number of packets sent

R

Uint64

177B

4

Port 14 Statistics – Number of packets sent

R

Uint64

177F

4

Port 15 Statistics – Number of packets sent

R

Uint64

1783

4

Port 16 Statistics – Number of packets sent

R

Uint64

1787

4

Port 17 Statistics – Number of packets sent

R

Uint64

178B

4

Port 18 Statistics – Number of packets sent

R

Uint64

178F

4

Port 19 Statistics – Number of packets sent

R

Uint64

1793

4

Port 20 Statistics – Number of packets sent

R

Uint64

1797

4

Port 21 Statistics – Number of packets sent

R

Uint64

179B

4

Port 22 Statistics – Number of packets sent

R

Uint64

179F

4

Port 23 Statistics – Number of packets sent

R

Uint64

17A3

4

Port 24 Statistics – Number of packets sent

R

Uint64

17A7

4

Port 25 Statistics – Number of packets sent

R

Uint64

17AB

4

Port 26 Statistics – Number of packets sent

R

Uint64

17AF

4

Port 27 Statistics – Number of packets sent

R

Uint64

17B3

4

Port 1 Statistics – Number of bytes received

R

Uint64

17B7

4

Port 2 Statistics – Number of bytes received

R

Uint64

17BB

4

Port 3 Statistics – Number of bytes received

R

Uint64

17BF

4

Port 4 Statistics – Number of bytes received

R

Uint64

17C3

4

Port 5 Statistics – Number of bytes received

R

Uint64

17C7

4

Port 6 Statistics – Number of bytes received

R

Uint64

17CB

4

Port 7 Statistics – Number of bytes received

R

Uint64

17CF

4

Port 8 Statistics – Number of bytes received

R

Uint64

17D3

4

Port 9 Statistics – Number of bytes received

R

Uint64

17D7

4

Port 10 Statistics – Number of bytes received

R

Uint64

17DB

4

Port 11 Statistics – Number of bytes received

R

Uint64

17DF

4

Port 12 Statistics – Number of bytes received

R

Uint64

17E3

4

Port 13 Statistics – Number of bytes received

R

Uint64

17E7

4

Port 14 Statistics – Number of bytes received

R

Uint64

17EB

4

Port 15 Statistics – Number of bytes received

R

Uint64

17EF

4

Port 16 Statistics – Number of bytes received

R

Uint64

17F3

4

Port 17 Statistics – Number of bytes received

R

Uint64

17F7

4

Port 18 Statistics – Number of bytes received

R

Uint64

17FB

4

Port 19 Statistics – Number of bytes received

R

Uint64

17FF

4

Port 20 Statistics – Number of bytes received

R

Uint64

1803

4

Port 21 Statistics – Number of bytes received

R

Uint64

1807

4

Port 22 Statistics – Number of bytes received

R

Uint64

180B

4

Port 23 Statistics – Number of bytes received

R

Uint64

180F

4

Port 24 Statistics – Number of bytes received

R

Uint64

1813

4

Port 25 Statistics – Number of bytes received

R

Uint64

1817

4

Port 26 Statistics – Number of bytes received

R

Uint64

181B

4

Port 27 Statistics – Number of bytes received

R

Uint64

181F

4

Port 1 Statistics – Number of bytes sent

R

Uint64

1823

4

Port 2 Statistics – Number of bytes sent

R

Uint64

1827

4

Port 3 Statistics – Number of bytes sent

R

Uint64

182B

4

Port 4 Statistics – Number of bytes sent

R

Uint64

182F

4

Port 5 Statistics – Number of bytes sent

R

Uint64

1833

4

Port 6 Statistics – Number of bytes sent

R

Uint64

1837

4

Port 7 Statistics – Number of bytes sent

R

Uint64

183B

4

Port 8 Statistics – Number of bytes sent

R

Uint64

183F

4

Port 9 Statistics – Number of bytes sent

R

Uint64

1843

4

Port 10 Statistics – Number of bytes sent

R

Uint64

1847

4

Port 11 Statistics – Number of bytes sent

R

Uint64

184B

4

Port 12 Statistics – Number of bytes sent

R

Uint64

184F

4

Port 13 Statistics – Number of bytes sent

R

Uint64

1853

4

Port 14 Statistics – Number of bytes sent

R

Uint64

1857

4

Port 15 Statistics – Number of bytes sent

R

Uint64

185B

4

Port 16 Statistics – Number of bytes sent

R

Uint64

185F

4

Port 17 Statistics – Number of bytes sent

R

Uint64

1863

4

Port 18 Statistics – Number of bytes sent

R

Uint64

1867

4

Port 19 Statistics – Number of bytes sent

R

Uint64

186B

4

Port 20 Statistics – Number of bytes sent

R

Uint64

186F

4

Port 21 Statistics – Number of bytes sent

R

Uint64

1873

4

Port 22 Statistics – Number of bytes sent

R

Uint64

1877

4

Port 23 Statistics – Number of bytes sent

R

Uint64

187B

4

Port 24 Statistics – Number of bytes sent

R

Uint64

187F

4

Port 25 Statistics – Number of bytes sent

R

Uint64

1883

4

Port 26 Statistics – Number of bytes sent

R

Uint64

1887

4

Port 27 Statistics – Number of bytes sent

R

Uint64

Interpreting the Port State Value

This section provides information for determining the port state.

In the following table, the upper byte repressents the interface state, and the lower byte represents the line protocol state.

Address

Description

Value

0x1700 to 0x171B

Port state information

Upper byte:

  • 0x0: Interface is down

  • 0x1: Interface is going down

  • 0x2: Interface is in the initializing state

  • 0x3: Interface is coming up

  • 0x4: Interface is up and running

  • 0x5: Interface is reset by the user

  • 0x6: Interface is shut down by the user

  • 0x7: Interface is being deleted

The lower byte:

  • 0x0: Line protocol state is down

  • 0x1: Line protocol state is up

Configure MODBUS

The MODBUS TCP server listens for MODBUS client requests on TCP port 502 by default. Port 502 is enabled when MODBUS server is started unless you configure a different port for MODBUS communications. The MODBUS server is disabled by default.


Note

MODBUS is supported only on standalone .

To configure MODBUS:

Before you begin

If a firewall or other security services are enabled, the switch TCP port might be blocked, and the switch and the client cannot communicate. If a firewall and other security services are disabled, a denial-of-service attack might occur on the switch. To add security when using MODBUS TCP, configure an ACL to permit traffic from specific clients or configure QoS to rate-limit traffic.

Procedure

Step 1

Enter global configuration mode:

configure terminal

Step 2

Enable MODBUS TCP on the switch:

scada modbus tcp server

To disable MODBUS on the switch and return to the default settings, enter the no scada modbus tcp server global configuration command.

The system displays a message to warn you that starting the MODBUS TCP server is a security risk:

WARNING: Starting Modbus TCP server is a security risk. Please understand the security issues involved before proceeding further. Do you still want to start the server? [yes/no]:

Step 3

Enter yes to confirm that you understand the security issues and to proceed with starting the server.

Step 4

(Optional) Set the TCP port to which clients send messages:

scada modbus tcp server port tcp-port-number

The range for tcp-port-number is 1 to 65535. The default is 502.

Step 5

(Optional) Set the number of simultaneous connection requests sent to the switch:

scada modbus tcp server connection connection-requests

The range for connection-requests is 1 to 5. The default is 1.

Step 6

Return to privileged EXEC mode:

end

Example

Switch# configure terminal
Switch(config)# scada modbus tcp server
WARNING: Starting Modbus TCP server is a security risk. Please understand the security issues involved 
before proceeding further. Do you still want to start the server? [yes/no]: y
Switch(config)# end

Displaying MODBUS Commands

Use the commands listed below to display information for MODBUS TCP.

Command

Purpose

show scada modbus tcp server

Displays the server information and statistics

show scada modbus tcp server connections

Shows information and statistics for each client connection

clear scada modbus tcp server statistics

Clears all the statistics for the Modbus server, including statistics for each client connection

The following is an example of the show scada modbus tcp server command and its output: 

Switch# show scada modbus tcp server
Summary: enabled, running, process id 142
Conn Stats: listening on port 801, 4 max simultaneous connections
    0 current client connections
    0 total accepted connections, 0 accept connection errors
    0 closed connections, 0 close connection errors
Send Stats: 0 tcp msgs sent, 0 tcp bytes sent, 0 tcp errors
    0 responses sent, 0 exceptions sent, 0 send errors
Recv Stats: 0 tcp msgs received, 0 tcp bytes received, 0 tcp errors
    0 requests received, 0 receive errors