AutomationDirect DL205 Manual

DL205 Analog Manual, 7th Edition Rev. D
4-13
Chapter 4: F2-08AD-1, 8-Channel Analog Current Input
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Writing the Control Program
Reading Values: Pointer Method and Multiplexing
There are two methods which can be used to read values, the pointer method and multiplexing.
The multiplexing method must be used when using a DL230 CPU. The multiplexing method
must also be used with remote I/O modules (the pointer method will not work). Either method
can be used with the DL240, DL250-1 and DL260 CPUs, but for ease of programming it is
strongly recommended to use the pointer method.
Pointer Method for the DL240, DL250-1, and DL260
The DL205 series has special V-memory locations (shown in tables on the following page)
assigned to each base slot that will greatly simplify the programming requirements. These
V-memory locations allow you to:
• specify the data format
• specify the number of channels to scan
• specify the storage locations
NOTE: DL240 CPUs with firmware release version 2.2 or later support this method. Also, DL250 CPUs with firmware
release version 1.06 or later support this method. If the DL230 example needs to be used, module placement in the base is
very important. Review the section earlier in this chapter for guidelines.
The example program shows how to setup these locations. Place this rung anywhere in the
ladder program, or, if RLL
PLUS
instructions are being used, in the Initial Stage.
This is all that is required to read the analog data into V-memory locations. Once the data is in
V-memory, it can be used to perform math, compare the data against preset values, etc. V2000
is used in the example but any user V-memory location can be used. The pointer method
automatically converts values to BCD.
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SP0
LD
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LDA
O2000
OUT
V7672
This loadsanoctal valuefor thefirst V-memory location that will be
used to storethe incoming data.For example, theO2000 entered
here would designatethe followingaddresses.
Ch1-V2000, Ch2-V2001, Ch3-V2002, Ch4-V2003
Ch5-V2004, Ch6-V2005, Ch7-V2006, Ch8-V2007
Theoctal address (O2000)isstoredhere. V7672isassigned to slot
2and acts as a pointer,which meansthe CPUwilluse theoctal
value in this location to determineexactly wheretostore the
incoming data.
OUT
V7662
SpecialV-memorylocationassigned to slot 2that contains the
number of channels to scan.
00
LD
Loadsaconstant that specifiesthe number of channelsto scanand
the dat aformat.The upperbyte, most significant nibble (MSN)
selects the dataformat(i.e. 0=BCD, 8=Binary), theLSN selectsthe
number of channels (i.e.1,2,3,4,5,6,7,8).
-or-
Thebinaryformatisusedfor displaying data on some operator
interfaces.The DL230/240CPUsdonot supportbinarymath
functions,whereas theDL250 does.
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AutomationDirect DL205 Specifications

General

Brand	AutomationDirect
Model	DL205
Category	Controller
Language	English