| Digital I/Os
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NPN and PNP are directional attributes of solid-state transistors. These
transistors have current amplification capability and are used as switches in a PLC.
Devices connected to the PLC must be specified as NPN or PNP. More and more devices today
are of the NPN category as they are easier to manufacture and perform better under most
conditions.
| NPN I/O only |
Nano-10, All FMD series (and T100MD+), F2424, Exp4040, E10-npn+, T22H-npn,
T28H-Relay, T44H-npn |
| PNP I/O only |
E10-Relay+, T44H-pnp |
| Both NPN & PNP |
F1616-BA, All T100MX+, T40H-Relay, T64H-Relay, EXP1616R |
The EXP1616R installation guide has wiring diagram for both NPN and PNP I/O inteface
which is applicable to other PLCs as well. You can download it here: http://www.tri-plc.com/inst-exp1616r.pdf
for a quick reference. |
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| Digital I/Os |
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| A transistor output is a solid-state device that handles small to medium
amount of current. Most transistor outputs in our PLC range can only handle DC current up
to the power supply voltage of the PLC. (i.e. either 12VDC or 24VDC). A relay is an
electrically operated switch. Current flowing through the coil of the relay creates a
magnetic field which attracts a lever and changes the switch contacts. This means that
relays allow one circuit to switch a second circuit which can be completely separate from
the first. If you need to switch AC voltages such as 24VAC, 110VAC or higher, you need to
select a PLC with RELAY output.
The following TRI PLCs
and Expansion boards incorporate relays in their output: |
Nano-10, F1616-BA, EXP1616R,
T100MX3224R+, E10-Relay+, T28H-Relay, T40H-Relay and T64H-Relay. |
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| Digital I/Os |
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| F-series |
You can add digital I/O expansion to any of the FMD PLCs via the EXP1616R
board, the EXP4040 board or both. Multiple expansion boards can be cascaded to increase
the number of digital I/Os up to the maximum limit. By default, all F-series PLCs can be
expanded up to 128 inputs and 128 outputs. |
| FMD series |
You can add digital I/O expansion to any of the FMD PLCs via the EXP1616R
board, the EXP4040 board or both. Multiple expansion boards can be cascaded to increase
the number of digital I/Os up to the maximum limit. By default, all FMD PLCs can be
expanded up to 128 inputs and 128 outputs. |
| Nano-10 |
The Nano-10 is intended to be a small application controller and as such
is not designed for expandability via expansion port like the larger FMD and F-series
models. However, since it can be a communication master on RS485 and Ethernet, it is
possible to add serial/Ethernet slave modules. The E10+ models are well suited to act as
serial I/O modules since multiple units can connect via RS485. Alternatively, 3rd party
Modbus modules or any other TRi PLCs could be used for I/O expansion as well. |
| T100MD+ |
You can add digital I/O expansion to any of the FMD PLCs via the EXP1616R
board, the EXP4040 board or both. Multiple expansion boards can be cascaded to increase
the number of digital I/Os up to the maximum limit. By default, all T100MD+ PLCs can
be expanded up to 96 inputs and 96 outputs. T100MD+ CPU with firmware version r47 or
later supports up to 128 inputs and 128 outputs using the SETSYSTEM 16,16 to override the
default limits. |
| T100MX+ |
The current T100MX+ PLC comprises two models: T100MX3224R+ and T100MX4832+
and they are not expandable. |
| E10+ |
The E-series is intended to be a small application controller and as such
is not designed for expandability. |
| H-Series |
The H-series has sufficient models for I/O range up to 64 and is
sufficient for most applications; no expandability has been designed in. |
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| Digital I/Os |
| How
can I connect REMOTE Digital I/Os to TRi PLCs? |
| All F-series, FMD series (and M-series), and Nano-10 'Super PLCs' can act
as a communication master to other TRi PLCs or to third party devices that support RS485
communication protocol such as Modbus. As such, the F-series/FMD series/Nano-10 'Super
PLCs' can easily use any other TRi PLCs as its remote I/O. The E10+ being small and low
cost are ideal to be deployed in a wide area network as remote I/Os as shown below: |
![rs485networkpic1[1].jpg (19187 bytes)](rs485networkpic1.jpg)
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| The TBASIC language incorporates a special command "NETCMD$"
which can be used to monitor/control any device that employs an ASCII based protocol
(including all TRi PLCs' native hostlink command). TBASIC also has built-in READMODBUS and
WRITEMODBUS commands which can be used to interface to any RTU that supports Modbus RTU
protocol. It is also possible for the Ethernet-equiped PLCs (F-series/FMD series/Nano-10
'Super PLCs') to communicate with devices that support Modbus TCP. As Ethernet in
automation is rapidly growing, more digital I/O and sensor module devices that can
communicate in Modbus TCP are now becoming available. |
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| Analog I/Os |
| What's the
difference between digital and analog I/Os? |
| A DIGITAL signal is a simple signal that is usually just
ON or OFF. An ANALOG signal has variations that are meaningful such as
inputs or outputs relating to level of temperature, light, sound, pressure, position, etc.
Most sensors produce very weak signal which needs to be amplified by special purpose
instrumentation amplifier called "Signal Conditioner" and the outputs from the
signal conditioner can then be connected to the PLC's analog inputs.
A Pulse Width Modulated (PWM) signal is a special method that
produces a variable voltage using an ON/OFF type digital I/O. It is neither a pure digital
nor a pure analog I/O and is discussed in the following FAQ question.
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| Analog I/Os |
| What
is a PWM (Pulse Width Modulated) Signal? |
| A Pulse Width Modulated (PWM) signal uses the duty cycle of a rapidly
switching digital I/O to represent a time-average variable. For example, if you turn ON a
digital output for 10ms, then turn it OFF for 90ms, and repeat this cycle indefinitely,
what you produce will be a rapidly pulsating waveform with a 10% ON duty cycle. If you use
a volt-meter to measure the output voltage of this waveform, what you will get is a
time-average reading which is equal to 10% of the peak voltage output when the digital
output is fully turned ON. Likewise, you can measure a PWM input signal by measuring the
ON time of the incoming pulses (the PULSEWIDTH), then divide it by the period of the
pulses (the PULSEPERIOD) to obtain the duty cycle. The actual measured quantities = duty
cycle x Full-Scale value.
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| Analog I/Os |
| When
do you need PLCs with analog I/Os? |
| The applications that need analog I/Os range widely, but some of the more
common ones in industry relate to the measurement and control of temperature, air/fluid
flow and motor speeds. For example, if you are trying to determine if something is
present or absent, you only need a digital input. But if you are trying to measure the
temperature in your room, you will need an analog input to the PLC.
Likewise, if your only means of controlling a heater is to turn it ON or OFF, then you
just need a digital output. But if you have the ability to control the speed of a motor by
applying a variable voltage of say between 0 to 5V DC, then you need an analog output from
the PLC.
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 Analog I/Os |
| Which
TRi PLCs provide Analog I/Os and PWM Output? |
All the F-series 'Super PLCs' include 4 channels of PWM output and a
number of analog I/Os built-in, as shown in the following table:
The F1616-BA has 12 Analog I/Os :
- 8 x AI - 12-bit 0-10V
- 4 x AO - 10-bit 0-10V |
The F2424 has 12 Analog I/Os :
- 8 x AI - 12-bit 0-5V
- 4 x AO - 10-bit 0-5V |
All the FMD series 'Super PLCs' include 4 channels of PWM output and a number of analog
I/Os built-in, as shown in the following table:
The FMD88-10 has 10 Analog I/Os :
- 8 x AI - 12-bit 0-5V
- 2 x AO - 10-bit 0-5V/0-10V switchable
- AO can be expanded to 4 channels with I2C-FRTC module installed (0-5V range only) |
The FMD1616-10 has 12 Analog I/Os :
- 8 x AI - 12-bit 0-5V
- 2 x AO - 10-bit 0-5V/0-10V switchable
- AO can be expanded to 4 channels with I2C-FRTC module installed (0-5V range only) |
The Nano-10 'Super PLC' includes 2 channels of PWM output and a 2
channels of analog inputs built-in, but no analog outputs are available. The analog input
channels are 0-5V only.
All the M-series 'Super PLCs' include built-in 2 channels of PWM output and a number of
analog I/Os as shown in the following table:
The T100MD1616 has 5 Analog
I/Os :
- 4 x AI - 10-bit 0-1V x2 and 0-5V x2
- 1 x AO - 8-bit (0-20mA) |
All the other M-series PLCs have 8 Analog I/Os :
- 6 x AI - 10 bit, 0-5V
- 2 x AO - 8 bit, 0-5V |
None of the H-series and E10 PLCs has analog I/Os and they also have no means of
interfacing to third party analog I/Os.
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Analog I/Os |
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| You can use a second, third or more FMD88-10 PLC to provide additional
low cost analog I/Os and 4 channel of PWMs per PLC to a master F-series or FMD series
'Super PLC'. The master and slave PLCs can communicate using their built-in RS485
interface over a low cost two-wire bus or, alternatively, over Ethernet. There are
built-in TBASIC commands to facilitate master/slave communications. Please see the
following webpage for more details: http://www.tri-plc.com/ioboard.htm#mstslave If
you require higher resolution analog I/Os, TRi carries a range of I-7000 series Analog I/O modules that
provides multiple channel of 16-bit analog inputs as well as 12-bit or 14-bit of analog
output.
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