Rockwell-automation 1770-KF2 Data Highway or Highway Plus Interface Mo Manual de usuario descargar pdf (Pagina 96)

Message Packet Formats

Chapter 5

5-17

Protected Bit Write

This command sets or resets individual bits within limited areas of the PC

data table memory. Its access is limited by memory access rungs in the

communication zone of the PC’s ladder diagram program.

The data field in this packet consists of 4-byte blocks, each of which

contains a 16-bit address field, a set mask, and a reset mask. Use the

ADDR field to specify the address of the byte to be modified in the PC

data table memory. Put the low byte (least significant bits) of the PC

address value into the first byte of the ADDR field. Refer to Chapter 6 for

more details on how to specify an address value.

Use the SET mask to specify which bits to set to 1 in the addressed PC

byte. A 1 in a bit position of the SET mask means to set the

corresponding bit in the addressed PC byte to 1; a 0 in a bit position of the

SET mask means to leave the corresponding bit in the PC byte

unchanged.

Use the RESET mask to specify which bits to reset to 0 in the addressed

PC byte. A 1 in a bit position of the RESET mask means to reset the

corresponding bit in the addressed PC byte to 0; a 0 in a bit position of the

reset mask means to leave the corresponding bit in the PC byte

unchanged.

Note that the interface module at the receiving PC station executes this

command by first making a copy of the addressed PC byte. It then sets or

resets the appropriate bits and writes the byte back into PC memory. At

the same time, the PC processor can be changing the states of the original

bits in memory. Because of this, some data bits may unintentionally be

overwritten.

Command

Format:

Reply Format:

TNSSTSCMD

SRCDST

TNSSTSCMD

SRCDST

ADDR

Up to 60 Masks of

This Format

SET ADDR SETRESET RESET

1 2 ... 91 92 93 94 95 96 97 98 99 100 101 ... 234 235

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Rockwell-automation 1770-KF2 Data Highway or Highway Plus Interface Mo Manual de usuario Pagina 96