GE GFK-1541B manual Type Value Decimal Description

3

(Word 12) Timeout for Each Read: Word 12 specifies the time (in hundredths of a second) the Ethernet Interface will wait for a read transfer to complete before setting the Channel Error bit and Detailed Channel Status words to indicate a non-fatal timeout error. The transfer can still complete even after a timeout occurs. As a result, an application can choose what to do if one occurs. If the timeout value is specified as zero, no timeout errors will be reported.

For most applications a timeout need not be specified because the read period, in effect, acts as a timeout. (Word 12 should be zero for no timeout). However, there are two special circumstances in which specifying a timeout is recommended:

ƒWhen the number of time units (Word 11) is zero, so that a subsequent transfer will be issued as soon as the previous transfer completes and no period errors are reported. In this case a timeout value can be specified so that timeout errors will be reported by the Channel Error bit.

ƒWhen 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. Valid values for Word 13 are listed below. The amount of data to be transferred is specified by the number of memory units of the data read from the remote PLC (Word 17).

Type

Value

(Decimal) Description

%L*	0	Program Block Local register memory (word mode)
%P*	4	Program register memory (word mode)
%R	8	Register memory (word mode)
%AI	10	Analog input memory (word mode)
%AQ	12	Analog output memory (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	Discrete temporary memory (byte mode)
	74	Discrete temporary memory (bit mode)
%M	22	Discrete momentary internal memory (byte mode)
	76	Discrete momentary internal memory (bit mode)
%SA	24	Discrete system memory group A (byte mode)
	78	Discrete system memory group A (bit mode)
%SB	26	Discrete system memory group B (byte mode)
	80	Discrete system memory group B (bit mode)
%SC	28	Discrete system memory group C (byte mode)
	82	Discrete system memory group C (bit mode)
%S	30	Discrete system memory (byte mode)
	84	Discrete system memory (bit mode)
%G	56	Discrete global data table (byte mode)
	86	Discrete global data table (bit mode)

Read-only memory, cannot be written to.

*Can only be accessed in the Remote PLC (%L and %P are available in Series 90-70 PLCs only).

3-12 TCP/IP Ethernet Communications for the Series 90™ PLC User's Manual– May 2002 GFK-1541B