KL5051 - Bidirectional SSI encoder interface

Register communication

 

Register access via process data exchange

Bit 7=1: Register mode
If bit 7 of the control byte is set, the first two bytes of the user data are not used for process data exchange but written into the register set of the terminal or read from it.
Bit 6=0: read, bit 6=1: write
Bit 6 of the control bytes is used to specify whether a register should be read or written.
Bit 6=0: A register is read without changing it. The value can be found in the input process image.
Bit 6=1: The user data are written into a register. The process is complete once the status byte in the input process image has returned an acknowledgment (see example).
Bit 0 to 5: Address
The address of the register to be addressed is entered in bits 0 to 5 of the control byte
 
 

Control byte in register mode (REG=1)

 
Bit
7
6
5
4
3
2
1
0
Name
REG=1
W/R
A5
A4
A3
A2
A1
A0
 

REG = 0bin: Process data exchange
REG = 1bin: Access to register structure

W/R = 0bin: Read register
W/R = 1bin: Write register

A5..A0 = register address
Addresses A5...A0 can be used to address a total of 64 registers.

Register mode control byte

The control or status byte occupies the lowest address of a logical channel. The corresponding register values are located in the following 2 data bytes. (The BK2000 is an exception: here, an unused data byte is inserted after the control or status byte, and the register value is therefore placed on a word boundary).

 
 

Example 1:
Reading of register 8 in the BK2000 with a KL5051 and the end terminal:

If the following bytes are transferred from the controller to the terminal,

Byte
Byte 3
Byte 2
Byte 1
Byte 0
Name
DataOUT 1
DataOUT 0
Not used
Control byte
Value
0xXX
0xXX
0xXX
0x88

The terminal returns the following type identifier (0x13BB corresponds to unsigned integer 5051)

Byte
Byte 3
Byte 2
Byte 1
Byte 0
Name
DataIN 1
DataIN 0
Not used
Status byte
Value
0xBB
0x13
0x00
0x88
 
 

Sample 2:
Writing of register 31 in the BK2000 with an intelligent terminal and the end terminal:

If the following bytes (code word) are transferred from the controller to the terminal,

Byte
Byte 3
Byte 2
Byte 1
Byte 0
Name
DataOUT 1
DataOUT 0
Not used
Control byte
Value
0x12
0x35
0xXX
0xDF

The code word is set, and the terminal returns the register address with bit 7 for register access as acknowledgment.

Byte
Byte 3
Byte 2
Byte 1
Byte 0
Name
DataIN 1
DataIN 0
Not used
Status byte
Value
0x00
0x00
0x00
0x9F