4

HWhen the read period is very long (minutes or hours). In this case a shorter timeout value can be specified so the application doesn't have to wait for the read period to expire before taking action.

(Word 13) Local PLC - Memory Type: Words 13-14 specify the location in the local PLC where the Ethernet Interface will store data received from the remote PLC. The size of this area is set by the size of the data read from the remote PLC (Word 17). The user is responsible for assuring that this area is large enough to contain the requested data without overwriting other application data. Valid memory types are listed in Table 4-2.

Table 4-2.

Series 90-70 PLC Memory Types

 

 

 

 

 

 

 

 

 

Value

 

 

Type

 

(Decimal)

Description

 

 

 

 

 

 

 

%L*

 

0

 

Program Block Local register memory (word mode)

 

%P*

 

4

 

Programregistermemory (word mode)

 

%R

 

8

 

Registermemory (word mode)

 

%AI

 

10

 

Analoginputmemory (word mode)

 

%AQ

 

12

 

Analogoutputmemory (word mode)

 

%I

 

16

 

Discrete input memory (byte mode)

 

 

 

70

 

Discrete input memory (bit mode)

 

%Q

 

18

 

Discrete output memory (byte mode)

 

 

 

72

 

Discrete output memory (bit mode)

 

%T

 

20

 

Discretetemporary memory (byte mode)

 

 

 

74

 

Discretetemporary memory (bit mode)

 

%M

 

22

 

Discretemomentary internal memory (byte mode)

 

 

 

76

 

Discretemomentary internal memory (bit mode)

 

%SA [

 

24

 

Discretesystemmemory group A (byte mode)

 

 

 

78

 

Discretesystemmemory group A (bit mode)

 

%SB [

 

26

 

Discretesystemmemory group B (byte mode)

 

 

 

80

 

Discretesystemmemory group B (bit mode)

 

%SC [

 

28

 

Discretesystemmemory group C (byte mode)

 

 

 

82

 

Discretesystemmemory group C (bit mode)

 

%S [

 

30

 

Discretesystemmemory (byte mode)

 

 

 

84

 

Discretesystemmemory (bit mode)

 

%G

 

56

 

Discrete global data table (byte mode)

 

 

 

86

 

Discrete global data table (bit mode)

[Read-onlymemory, cannot be written to. * Can only be accessed in the Remote PLC.

(Word 14) Local PLC - Memory Starting Address: Word 14 specifies the starting address in the local PLC in which the data from the remote PLC is to be stored (1-based).

(Word 15) Remote PLC - Memory Type: Words 15-16 specify the memory type and starting address in the remote PLC from which the data is to be read. Valid values for Word 15 are given in Table 4-2. If %P memory is used, you must specify a Program name in words 24 - 27. If %L memory is used, you must specify a Program name in words 24 - 27 and a Program Block name in words 28 - 31.

(Word 16) Remote PLC - Memory Starting Address: Word 16 specifies starting address in the remote PLC from which the data is to be read (1-based). Valid ranges of values depend on the remote PLC .

(Word 17) Remote PLC - Number of Memory Units: Word 17 specifies the number of bits, bytes or words to be read, determined by the remote PLC memory type specified. For example, if the memory type is %I in bit mode this is the number of bits. If the

GFK-1004B

Chapter 4 Programming Communications Requests

4-13

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GE GFK-1004B user manual Series 90-70 PLC Memory Types, Value Type Decimal Description