APC 6000 user manual Function 3 and 4 read N words, Function 5 writing a bit

JBUS protocol (continued)

Function 3 and 4: read N words

The number of words must be less than or equal to the word field size (see memory board).

◗function 3: read output or internal words;

◗function 4: read input words.

request
slave address	3 or 4	adress of			number of				CRC 16
		first bit			words
		MSB	LSB		MSB	LSB
1 byte	1 byte	2 bytes			2 bytes			2 bytes
response
slave address	3 or 4	number of		first word		last word				CRC 16
		bytes read
				PF	pf	PF	pf
1 byte	1 byte	1 byte		2 bytes		2 bytes				2 bytes

example

Reading words at location 146 to 14B of slave at address 28H (voltage fields)

request:
28	03	0146		06	A7 E0
response:
28	03	0C	XXXX			YYYY	CRC 16

word 0146 word 014B

Function 5: writing a bit

request

slave address	5	bit address	bit value		0
1 byte	1 byte	2 bytes	1 byte		1 byte
				write 0
		bit set to 0
		bit set to 1		write FF

CRC 16

2 bytes

response

slave address

5

bit address

bit value

0

CRC 16

In function 5 the response and request frames are identical.

example

Setting bit location C05 to 1 of slave at address 40H (inverter on)

request:

40 05 0C05 FF 00 90 7A

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