CAT EMCP 4 - 7.4 SECURITY - READING AND GAINING ACCESS

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Application and Installation Guide EMCP 4 SCADA Data Links

Request: 0x 01 03 00 C7 00 01 xx xx

0x 01 = slave address of EMCP 4

0x 03 = function code (Read Registers)

0x 00 C7 = Engine Oil Pressure

0x 00 01 = register count (1 register)

Response: 0x 01 03 02 FF FF xx xx

0x 01 = slave address of EMCP 4

0x 03 = function code (Read Registers)

0x 02 = byte count (2 bytes = 1 register)

0x FF FF = 65535. 65535 × 0.125 kPa/bit = 8191.375 kPa.

But the data range for Engine Oil Pressure (200) is 0 to 8031.875 kPa (see Appendix A). Therefore this

data is invalid. Now suppose the Engine Oil Pressure Sensor Configuration setpoint is changed to

Sensor. If the input is configured correctly, and the oil pressure is reading correctly on the Engine

Overview screen (refer to the EMCP 4 Application and Installation Guide for information on using the

EMCP 4 display). Now re-reading while the engine is stopped:

Request: 0x 01 03 00 C7 00 01 xx xx

0x 01 = slave address of EMCP 4

0x 03 = function code (Read Registers)

0x 00 C7 = Engine Oil Pressure

0x 00 01 = register count (1 register)

Response: 0x 01 03 02 00 00 xx xx

0x 01 = slave address of EMCP 4

0x 03 = function code (Read Registers)

0x 02 = byte count (2 bytes = 1 register)

0x 00 00 = 0. 0 × 0.125 kPa/bit = 0 kPa.

This value is within the data range of 0 to 8031.875 kPa. Therefore this data is valid.

7.4 SECURITY – READING AND GAINING ACCESS

This example demonstrates setting a password, and then entering the password to gain access to a

certain SCADA security level. There are also some examples given of valid versus invalid passwords.

Assume the EMCP 4 contains default values – all three user-configurable passwords (SCADA, Level 1,

and Level 2) are disabled.

Read and verify the current security level (Step 1):

Request: 0x 01 03 02 DB 00 01 xx xx

0x 01 = slave address of EMCP 4

0x 03 = function code (Read Registers)

0x 02 DB = Current Security Level

Response: 0x 01 03 02 00 02 xx xx

0x 02 = byte count (2 bytes = 1 register)

0x 00 02 = security access level 2.