Cutler-Hammer D320 PLC, User Manual

Page: 214 / 258

202
D320 PLC User's Manual
CPU ID
All devices connected to the network need a network ID number for communication. There is an
available range of 0 to 191 network ID numbers. Redundancy is not permitted. When a single PLC and
a peripheral device are connected, usually 0, 1, or 255 is assigned as the network ID number to the
PLC. When the peripheral device wishes to communicate to a connected PLC regardless of its
programmed network ID number, it can use global network ID number 255, to which any PLC will
respond. When several CPU modules are connected to one communication network, they must use
individual ID numbers from 0 to 191. The PLC’s network ID number is configured using the GPC
program loader software.
Function Codes Included in the Query
•
Each function code is 1 byte. When the PLC receives a query (Q), the function code of the
final response (R) is formed by adding $80 (hex) to the function code sent by the query.
•
The function code of the R message can be used by the peripheral device to verify that the
correct Q message has been received by the PLC.
Communication function
* $ notes hexadecimal notations
Communication Function Query Function Code Response Function Code
Read Bits $01 $81
Write Bits $02 $82
Read Words $03 $83
Write Words $04 $84
Read Bits and Words $05 $85
Write Bits and Words $06 $86
Read Program $07 $87
Write Program $08 $88
Read Instruction $09 $89
Change Instruction $0A $8A
Change Parameter $0B $8B
Insert Instruction $0C $8C
Delete Instruction $0D $8D
Find Instruction $0E $8E
Find Parameter $0F $8F
Delete Section $10 $90
No Service $00 $00
Note: Function codes $07 to $10 are used for programming and system control functions, and are
beyond the scope of this manual. Please contact Cutler-Hammer technical support for more
information.
Note: The bit/word address assignment uses the absolute address method for reading memory
locations. (See Chapter 5 for memory map.)