AutomationDirect DL205 Manual

DL205 Analog Manual, 7th Edition Rev. D
5-14
Chapter 5: F2-08AD-2, 8-Ch. Analog Voltage Input
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Writing the Control Program
Reading Values: Pointer Method and Multiplexing
There are two methods of reading values:
• The pointer method
• 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 CPUs
The DL205 series has special V-memory locations 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. 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 in the initial stage if stage programming instructions are being used. This
is all that is required to read the data into V-memory locations. Once the data is in V-memory
math can be used on the data, compare the data against preset values, and so forth. V2000 is
used in the example but any user V-memory location can be used. In this example the module
is installed in slot 2. Be sure to use the V-memory locations for the module placement. The
pointer method automatically converts values to BCD (depending on the LD statement in the
ladder logic).
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SP0
LD
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LDA
O2000
OUT
V7672
This loads an octalvalue forthe firstV-memorylocationthat will be
used to storethe incoming data. Forexample, theO2000 entered
herewoulddesignate thefollowing addresses.
Ch1--V2000, Ch2--V2001, Ch3--V2002,Ch4 -- V2003
Ch5-V2004, Ch6-V2005, Ch7-V2006,Ch8 -V2007
Theoctal address(O2000)isstoredhere. V7672isassignedtoslot
2 and acts as a pointer,whichmeans theCPU will usethe octal
value in this location to determine exactlywhere to storethe
incoming data.
OUT
V7662
Special V-memory location assignedtoslot2that contains the
numberofchannelsto scan.
00
LD
Loadsaconstant that specifies the numberofchannelstoscan and
thedataformat.The upperbyte, most significant nibble (MSN)
selects the dataforma t(i.e. 0=BCD, 8=Binary), theLSN selects the
numberofchannels(i.e. 1, 2, 3, 4, 5, 6, 7, or 8).
-or-
Thebinaryformatisusedfor displayingdataonsom eoperator
interfaces.The DL230/240 CPUs do notsupport binarymath
functions, whereasthe DL250 does.
08 K0088

AutomationDirect DL205 Specifications

General

Brand	AutomationDirect
Model	DL205
Category	Controller
Language	English