DL405 CPUs
DL405 CPUs - Which one should I choose?
There are many things to consider when choosing a CPU.
Select one of the links below to help you make your decision:
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System capacity
System capacity is the ability of the CPU to accommodate a variety of
applications. Here are a few key considerations when determining system capacity:
- How much memory do you need?
Consider both ladder memory and data registers (V-memory). For ladder memory, most boolean
instructions require one word. Some other instructions, such as timers, counters, etc.
require two or more words. Our Vmemory locations are 16-bit words and are useful for data storage,
etc.
- What type of memory do you need?
The D4-430 only has built-in EEPROM memory for the ladder program. The
D4-440 requires a memory cartridge, and you have a choice of several sizes and
memory types. The D4-450 has 7.5K of built-in flash ladder memory, but you
can also use a memory cartridge instead of the built-in memory.
- How many I/O points are required?
You will need to know how many field devices are required. Each CPU supports
a different amount of local, expansion, and remote I/O. Check the Specifications tables to
determine which CPU meets your application requirements.
- Are there any remote I/O points?
In many applications, the wiring cost of bringing the individual control wiring
back to the PLC control panel can be reduced by the use of remote I/O. All
DL405 CPUs can support remote I/O. The D4-450 CPU has built-in remote I/O connections on the
bottom 25-pin port!
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Performance
If you have a time-critical application where every millisecond is important,
then choose the CPU with the fastest overall scan time. For applications that
only require boolean instructions(contacts and coils), the D4-440 is the
fastest. However, if you use a few simple math or data instructions, then choose
the D4-450. The D4-450 is considerably faster at performing even the most basic of math
or data instructions and will provide a faster overall scan time.
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Programming and diagnostics
Our CPUs offer an incredible array of instructions and diagnostic features
which can save you many hours of program and debug time. From basic
boolean contact logic to PID and floating point math, we have it covered! A chart
is available that covers some of the basic instruction categories, but for more
details, see the complete list of instructions.
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Built-in CPU communications
Every DL405 CPU provides at least two built-in communications ports. Each
DL405 CPU supports our DirectNET protocol on the bottom port for easy,
economical networking. Need MODBUS? Then check our D4-450 CPU, which has built-in MODBUS
RTU Master and Slave capability. Of course, we also offer a wide array of communications, such
as our Ethernet Communications Module, Data Communications Module, MODBUS Master and MODBUS Slave Modules.
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Specialty I/O modules
In addition to our cost-effective discrete and analog I/O, we also offer a wide array
of specialty modules to solve the really tough applications. Our D4-430 and D4-440 only support
specialty modules in the local base (CPU base). Our D4-450 CPU supports specialty modules in
the local CPU base as well, but it can also support selected specialty modules in
expansion bases if you use our D4-xxB-1 bases (xx is the number of slots). If you are considering
a D4-450 CPU, there may be some restrictions on using speciality modules.
The D4-450 provides all the capabilities of the D4-430 and D4-440 CPUs, plus several additional features.
It offers an incredible array of features for a CPU that costs so little.
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Built-in CPU communications ports
The D4-450 offers four built-in ports for extra convenience. The 15-pin port offers
our proprietary K-sequence protocol and is primarily used for programming connections to a D4-HPP-1
handheld programmer or to a PC running DirectSOFT32 software. It can also be
used to connect to an EZText/Touch panel or other operator interfaces. The 6-pin phone jack also
supports K-sequence, plus it can be a DirectNET slave port or an ASCII output port. The
bottom 25-pin port contains two logical ports with different pins for each port. It is primarily
a networking port that supports DirectNET master/slave or MODBUS master/slave protocols.
The bottom port can also be used as an ASCII output port for connections to printers or other devices
that can accept ASCII input. A Communications Ports table is available that offers a complete description
of each port.
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16-PID loops
The D4-450 CPU can process up to 16 PID loops directly in the CPU. You can
select from various control modes including automatic control, manual control, and cascade control.
There are a wide variety of alarms including Process Variable, Rate of Change, and Deviation.
The various loop operation parameters are stored in V-memory, which allows easy access from operator
interfaces. Setup is accomplished with our DirectSOFT32 Programming Software.
An overview of the various loop specifications and features is available.
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Floating-point math
The D4-450 CPU supports IEEE format floating-point math calculations. This feature means the D4-450
includes full trigonometric functions and various forms of integer/floating point number
conversions.
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Power supplies
We offer a choice of three power supplies for the DL450 CPU. The power supplies
are built into in the CPU. Available power supplies are:
- D4-450 - 110/220V AC version
- D4-450DC-1 - 24V DC version
- D4-450DC-2 - 125V DC version
The D4-450 CPU provides several scan control options, which are useful in some
high-speed machine control applications.
Variable — The scan varies as necessary from scan to scan. The actual scan time
depends on the instructions being executed.
Limited — This is similar to a variable scan in that the scan varies as necessary.
However, if the actual scan time exceeds a specified target scan time, then a scan
overrun condition is indicated.
Fixed — If the scan is finished before the time specified, idle time is added to ensure a
fixed scan period. If the scan exceeds the time specified, the scan is extended to
ensure all instructions are executed. A scan overrun condition is also reported.
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Memory
The D4-450 has 7.5K of flash memory on board. Upgrade to 15.5K by choosing an optional memory cartridge.
The memory cartridge is recommended since it is removable in the event of problems.
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Full array of instructions
Imagine if someone asked you to write a book, but then told you that you could only use 50 different words?
That would be a tough job! The same is true for writing a PLC program. The right instruction can greatly
simplify your control program. The D4-450 supports over 200 powerful instructions. These include:
- Four types of drum sequencers, each with 16 steps and up to 16 outputs
- Leading and trailing edge triggered oneshots
- Bit of word manipulation (bit set, reset, etc.)
- Trigonometric functions
- Floating point conversions
PID Loop Specifications and Key Features
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Number of Loops - Selectable, 16 maximum
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CPU V Memory Required - 32 V locations per loop selected (An additional 32 V locations per loop
required if using Ramp/Soak)
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PID Algorithm - Position or velocity form of the PID equation. Optionally specify direct or reverse
acting, square root of the error and error squared control.
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Auto Tuning - Open loop step response method and closed loop limit cycle method.
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Sample Rate Specify the time interval between PV samples, 0.05 to 99.99 in units of seconds or
minutes. If using all 16 loops, the smallest sample rate is limited to either 0.2 seconds or
(PLC scan time x number of loops).
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Loop Operation Modes - Loop can be in automatic control, manual (operator) control, or cascade
control. PV alarm monitoring continues when loops are in manual mode.
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Ramp/Soak - Up to 16 steps (8 ramp, 8 soak) per loop, with indication of Ramp/Soak step.
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Square Root PV - Specify a square root of the PV for a flow control application.
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Limit SP - Specify a maximum and minimum value for allowable setpoint changes.
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Limit OUT - Specify a maximum and minimum value for the output range.
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Gain - Specify proportional gain of 0.01 to 99.99.
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Reset - Specify integral time of 0.1 to 99.98 in units of seconds or minutes.
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Rate - Specify the derivative time, 0.00 to 99.99 seconds.
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Rate Limiting - Specify a derivative gain limiting coefficient to filter the PV used in calculating
the derivative term (0 to 20).
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Bumpless Transfer I - Bias and setpoint are initialized automatically when the loop is switched from
manual to automatic. This provides for a bumpless transfer, which reduces the chance of sharp changes
in the output as a result of entering automatic mode.
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Bumpless Transfer II - Bias is set equal to the Output when the module is switched from manual to
automatic. This allows switching in and out of automatic mode without having to re-enter the setpoint.
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Step Bias - Provides proportional bias adjustment for large setpoint changes. This may stabilize the
loop faster and reduce the chance of the output going out of range. Step bias should be used in
conjunction with the normal adjusted bias operation.
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Anti-windup - If the position form of the PID equation is specified, the reset action is stopped
when the PID output reaches 0 or 100%. Select adjusted bias or freeze bias operation.
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Error Deadband - Specify an incremental value above and below the setpoint in which no change in
output is made.
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Error Squared - Squaring the error minimizes the effect a small error has on the Loop output,
however, both Error Squared and Error Deadband control may be enabled.
Alarm Specifications
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Deadband - Specify 0.1% to 5% alarm deadband on all alarms except Rate of Change.
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PV Alarm Points - Specify PV alarm settings for low-low, low, high, and high-high conditions.
You can also specify a deadband to minimize the alarm cycles when the PV approaches alarm limits.
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PV Deviation - Specify alarms to indicate two ranges of PV deviation from the setpoint value
(yellow and red deviation).
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Rate of Change - Specify a rate-of-change limit for the PV.
Need Temperature Control?
If you're only interested in controlling temperature, then there may be a better solution than the D4-450 CPU.
Check out the F4-4LTC module. This module has the capabilities of our single loop controllers built into one
economical module! Detailed specifications are available. This module can directly control
up to four loops and it even includes built-in relay outputs for heater or chiller control! If you use the
built-in PID capability of the D4-450 CPU, you still have to purchase the analog input modules and the output
modules (either discrete or analog) in order to complete the loop. This can result in a much higher overall
cost when compared to the F4-4LTC.
D4-440/430 Key Features
D4-440 CPU
The D4-440 provides a subset of the D4-450’s capabilities. If you need fast
boolean execution, good communications, and complex math or PID isn’t required, this is the CPU for you!
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Instruction set
The D4-440 instruction set includes most of the capabilities of the D4-450. The D4-440 does not support
some of the more advanced instructions such as PID, floating point math, drum sequencers, trig.
functions, etc.
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Two built-in communication ports
The D4-440 offers two communication ports. The top port can be used for a direct connection to a
personal computer for programming, to our handheld programmer, or to our DV-1000, operator
interfaces or touch panels. The bottom port is a slave-only port and supports our DirectNET or
K-sequence protocol at speeds up to 19.2K baud.
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Range of power supplies
The D4-440 provides a wide range of power supply options. A 110/220VAC version, a 24 VDC version, and a
125VDC version are available.
Memory cartridges
A table is provided that shows the memory cartridges available for the D4-440 and
D4-450. The D4-440 requires a memory cartridge for program storage. The D4-450 has 7.5K of built-in
FLASH program memory. However, you can use a memory cartridge instead of the built-in memory if you need more
program space. (The D4-430 has built-in program memory and cannot use a memory cartridge.)
The D4-430 is the most economical CPU in the DL405 product family. If
you are primarily looking at the DL405 because of I/O form factor or reasons
that don’t require tons of CPU horsepower, try the D4-430.
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Two built-in communication ports
The D4-430 also offers two communication ports. The top port can be used for a
direct connection to a personal computer for programming, to our handheld
programmer, or to the DV-1000, operator interfaces or touch panels. The
bottom port is a slave only port and supports DirectNET protocol at speeds
up to 19.2K.
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Built-in EEPROM memory
One advantage for the D4-430 is 3.5K of built-in EEPROM program memory. A
memory cartridge is not required.
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