PKW Objects - TeSys Tera Motor Management System

Overview

The LTMT main unit supports PKW. The PKW feature consists of:

Four input words mapped in input assembly objects 111, 112, and 113
Four output words mapped in output assembly objects 101, 102, and 103

These four words tables enable a EtherNet/IP scanner to read or write any register using I/O messaging.

As shown in the table below, the PKW area is located at the beginning of the corresponding assembly objects 112, 113, 102, and 103.

PKW OUT Data

PKW OUT data requests from the EtherNet/IP scanner to the LTMT main unit are mapped in assembly objects 101, 102, and 103.

To access registers, select one of the following function codes:

R_REG_16 (0x25) to read 1 register
R_REG_32 (0x26) to read 2 registers
W_REG_16 (0x2A) to write 1 register
W_REG_32 (0x2B) to write 2 registers

Word 1	Word 2			Word 3	Word 4
Word 1	MSB		LSB	Word 3	Word 4
Register address	Toggle bit (bit 15)	Function bits (bits 8 - 14)	Not used (bits 0 - 7)	Data to write
Register number	0 / 1	R_REG_16Code 0x25	0x00	–	–
		R_REG_32Code 0x26		–	–
		W_REG_16Code 0x2A		Data to write in register	–
		W_REG_32Code 0x2B		Data to write in register 1	Data to write in register 2

Any change in the function code triggers the handling of the request (unless function code [bit 8 to bit 14] = 0x00).

NOTE: The highest bit of function code (bit 15) is a toggle bit. It is changed for each consecutive request.

This mechanism enables the request initiator to detect that a response is ready by polling bit 15 of the function code in word 2. When this bit in the OUT data becomes equal to the response emitted toggle bit in the IN data (when starting the request), then the response is ready.

PKW IN Data

PKW IN data response from the LTMT main unit to the EtherNet/IP scanner are mapped in assembly objects 111, 112, and 113.

The LTMT main unit echoes the same register address and function code or, eventually, a detected error code.

Word 1	Word 2			Word 3	Word 4
Word 1	MSB		LSB	Word 3	Word 4
Register address	Toggle bit (bit 15)	Function bits (bits 8 - 14)	Not used (bits 0 - 7)	Data to write
Same register number as in the request	Same as in the request	ErrorCode 0x4E	0x00	Error code
		R_REG_16Code 0x25		–	–
		R_REG_32Code 0x26		Data read in register	–
		W_REG_16Code 0x2A		Data read in register 1	Data read in register 2
		W_REG_32Code 0x2B		–	–

If the initiator tries to write a TeSys Tera object or register to an unauthorized value, or tries to access an inaccessible register, a detected error code is returned (Function code = toggle bit + 0x4E). The detected error code can be found in words 3 and 4. The request is not accepted and the object/register remains at the old value.

To re trigger exactly the same command, you need to:

Reset the function code to 0x00.
Wait for the response frame with the function code equal to 0x00.
Reset it to its previous value.

This is useful for a limited primary like an HMI.

Another way of re-triggering exactly the same command is to invert the toggle bit in the function code byte.

The response is valid when the toggle bit of the response is equal to the toggle bit written in the answer (this is a more efficient method, which requires higher programming capabilities).

PKW Detected Error Codes

Case of a detected write error:

Detected Error Code	Detected Error Name	Explanation
3	FGP_ERR_REGISTER_NOT_FOUND	Register not managed (or the request needs super user access rights)
7	FGP_ERR_INVALID_FUNCTION_OR_ADDRESS	Using an undefined PWK function code or read/write to an undefined register address.

Case of a detected read error:

Detected Error Code	Detected Error Name	Explanation
3	FGP_ERR_REGISTER_NOT_FOUND	Register not managed (or the request needs super user access rights)
7	FGP_ERR_NOT_ALL_REGISTER_FOUND	One or both registers cannot be found

Class Code

The PKW Object class code is 0xC5, vendor specific definition.

Class Attributes

Attribute ID	Name	Access	Description
0x01	Revision	–	The PKW Object implementation revision. Returns 0x01.
0x02	Maximum instance	–	Returns 0x01 to represent a single instance.
0x03	Number of instances	–	The number of object instances. Returns 0x01.
0x06	Maximum class attribute	–	The largest class attribute value. Returns 0x07.
0x07	Maximum instance attribute	–	The largest instance attribute value. Returns 0x02.

Class Services

Service Code	Name	Description
0x01	Get attribute all	Returns the value of all class attributes.
0x0E	Get attribute single	Returns the value of the specified attribute.

Instance Codes

Only one instance is implemented: Instance 1.

Instance Attributes

Attribute ID	Name	Access	Description
0x01	Request object	–	Array of eight bytes to represent the PKW request.
0x02	Response object	–	Array of eight bytes to represent the PKW response.

Instance Services

Service Code	Name	Description
0x0E	Get attribute single	Returns the value of the specified instance attribute.
0x10	Set attribute single	Modifies the instance attribute value with the access type of RW.