Wx-TERM16 – 16 In, 14 Out + 4 AO Terminals

Wx-TERM16 is a DIN-rail mountable terminal module that provides a Wx100 PLC with detachable screw terminals to enable quick field wiring.

A Wx-TERM16 provides Wx100 PLC with the following number of I/Os:

I/O Types:	Qty	Specifications
Digital Inputs:	16	12 to 24VDC, PNP or NPN
Analog Inputs:	6 (shared terminal with D.I.)	0.5V to 5V, 12-bit resolution
Digtal outputs:	14	12 to 24VDC, NPN
Analog outputs:	4	2 channels: 0-20mA 2 channels: 0-5V

In addition, Wx-TERM16 also has an expansion header that allows it to connect to expansion modules to add additional analog and digital I/Os to the PLC.  Current Wx100 hardware and operating system firmware supports up to additional 64 digital/analog inputs and 64 digital outputs. Wx100 thus has the capability to handle application that uses a few I/Os to larger equipment that requires up to 160 I/Os.

 

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There are two ways to install the Wx-TERM16

a) Install on DIN Rail

It is really simple to mount the Wx-TERM16 on a DIN-rail – simply pull down the “DIN-Rail Locking Tab” down until it clicks and stay in place. Next hook the Wx100 over a 1″ DIN rail, and push the locking tab back into its original position and the enclosure will stay in place on the DIN rail.

The enclosure may still slide along the DIN rail to make it easy to adjust its location. If you need to lock the enclosure in place you can add a 6-32 x  1″ (or M3.5 x 25mm) screw to one of the fastening tabs to add some friction against the back wall of the control panel.

b) Fasten with Screws

There are two fastening tabs on the upper and lower side of the Wx-TERM16 body enclosure. Simply drill a pilot hole through the fastening tab and use an M3 or 1/8″ diameter self-tapping screw to fasten the Wx-TERM16 enclosure to the control panel.

 

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Note:

• In the next few sections we will describe in greater details how the power supply, the digital inputs and digital outputs should be wired to the Wx-TERM8 board.
• The specifications and programming methods for the analog I/Os are detailed in Chapter 5 and Chapter 6 in the Wx100 User’s Manual. Chapter 6  further shows how the special inputs and outputs such as quadrature encoder, stepper motor driver etc. are mapped to the Wx100 digital I/Os.

 

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a) PLC and I/O Using Same Power Supply

Wx-TERM16 can be powered by a regulated switching or linear power supply between 12V to 24VDC (+/- 5% ripple) and 2A to 5A current capacity. The same power supply can be used to power both the Wx-TERM16 and the Wx100 PLC.

The power supply to the Wx-TERM16 is normally connected to the bottom left screw terminals marked as “POWER IN” on the Wx-TERM16 as shown in the wiring diagram in the last section. The power supply inputs are in-turn routed by the Wx-TERM16 PCB to all the V+ and 0V terminals adjacent to the INPUT and OUTPUT terminal sections for easy connection to I/O devices. Hence, power supply input may also be supplied through any of these V+ and 0V terminals too.

Note:

Internally, the Wx-TERM16 also routes its power supply (via a reverse blocking diode) to the Wx100 via pin19 and 20 on the ribbon cable. This means that Wx100 PLC will receive power even if you don’t connect the power supply cable to the PLC’s own power supply screw terminals. However, we strongly recommend that you wire a separate pair of wire to power the Wx100 through its own power supply input terminals (please refer to Wx100’s User Manual for details).
 

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When used with Wx-TERM16, The Wx100 will have a total of 16 digital inputs. Input #1 to #6 also be used a 12-bit 0-5V analog inputs. Inputs # 3 to #8 can also be used a special high speed digital inputs for pulse measurement and high speed counters.

To simplify field wiring, the power input (V+ and 0V) that Wx-TERM16 receives via its “POWER IN” connectors are routed by the Wx-TERM16 PCB to the input terminal section.

a) PNP Connection

All Wx100 PLC digital Input are PNP (current sink) by default. This means that to turn ON the digital input you need to supply it a high positive voltage >=+8V. To turn off the digital input you need to supply it <= +3V.

Input Voltage for Logic 0:	Open Circuit or 0 to 3VDC
Input Voltage for Logic 1:	+8V to +30VDC

Each digital input has a green LED indicator which lights up when the input is turned ON. Connecting to a mechanical switch or push button is extremely simple – it only needs to short the V+ to the IN terminal as shown in (a) below. PNP sensors that are powered from 12 to 24V DC is just as easily connected as shown as (b) in Figure 1.5

b) NPN Connection

NPN (current sink) sensors work in reverse to PNP sensors in that when it turns ON it will want to pull the input to low voltage, whereas when it turns ‘OFF’ it will either leave the input floating or pull it up to the power supply voltage level.

By connecting the “Pullup” terminal to V+, each digital input in the group (e.g. IN1,IN2,IN3 & IN4 are in one group, IN5 to IN8 are in another group, and so on) will be pulled up to V+ via its individual internal 3.3K 0.5W pullup resistor. This means that by default the digital input is turned ON (the green LED will light up) even if the sensor is not connected or sensor output an OFF state. When the NPN sensor turns ON it will pull the input to low, essentially turning OFF the PLC digital input. This means that the NPN sensor behaves in negative logic to the PLC. When Pullup is connected to V+: Input Voltage for Inverted Logic 0: Open Circuit or +8V to +30V Input Voltage for Inverted  Logic 1: 0V to +3V

Fortunately, you don’t have to think in term of negative logic when you write the PLC program. By running the special INVERT_INPUTS command once during initialization of the PLC program, you can force the PLC firmware to invert the logic of specified inputs before processing. This includes the digital I/O scan as well as all interrupt-based input functions such as pulse monitoring and high-speed counter operation:

INVERT_INPUTS ch, n

ch	Every 16 digital inputs are grouped into 1 channel the same way as is defined by the system variable INPUT[ch]. Wx supports up to 5 digital inputs channel = 16 x 5 = 80 digital inputs.
n	bit within the channel to be inverted. Any bit that is a ‘1’ in n will signal to the firmware that the corresponding physical input bit is to be inverted during I/O scan or when it is processed by an interrupt service routine.

E.g. If you are connecting only IN1 and IN2 to NPN sensors and the rest to PNP, that means you should set bit 0 and bit 1 to ‘1’ and the rest to ‘0’. So you should run this command:

INVERT_INPUTS 1, &H000F ‘ Only inputs 1 to 4 are inverted

If you are connecting first 8 inputs to NPN sensors, then run this command:

INVERT_INPUTS 1, &H00FF ‘ Inputs 1 to 8 are all inverted. Inputs 9 to 16 are not inverted.

 

Note:

1. Run the INVERT_INPUTS ch, n command as early as possible in your PLC program. Ideally it should be the first statement inside an INIT custom function triggered by a SCAN contact at the first rung of the ladder logic.
2. An input that belongs to the input group where the “Pullup” signal is connected to V+ can no longer be configured as an analog input. Thus, if you have a system that needs to connect to analog, PNP and NPN sensors we recommend that you configure IN7 to IN16 (if available) as the NPN inputs since these inputs are not configurable to be analog inputs in the first place.
3. Although the ON/OFF input indicators on the i-TRiLOGI online monitoring screen will show correctly the input state of the input corresponding to its defined logic type (either positive or negative logic), the actual green LEDs of the digital inputs will continue to only light up in positive logic mode (i.e. when the input voltage is > 8V) even if an input has already been configured as an NPN input. This should be clearly stated in the service manual for your maintenance technicians to avoid confusion.

 

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When used with Wx-TERM16, The Wx100 will be able to control a total of 14 digital outputs. Output #1 to #6 can be configured as special high speed outputs such as PWM or stepper control. Output #7 to #14 are regular digital outputs.

All digital outputs on the Wx-TERM16 are NPN output type – meaning that when an output is turned ON it will sink current from the load (i.e. connecting the load to the 0V). The correct way to wire the load to the PLC’s digital output is to connect the high side voltage (either the V+ or another positive voltage from the load’s power supply) to “+” input lead of the load, and connect the “-” input lead of the load to the PLC’s digital output.

To simplify field wiring, the V+ power input that Wx-TERM16 receives via its “POWER IN” connector is routed by the Wx-TERM16 PCB to the output terminal section. This allows user to very easily wire to a typical output load. For example, the following shows how to easily use it to turn on a 12V lamp load. By configuring the digital output as a PWM output you can also control how much power to supply to the lamp and thus control the brightness in software.

The load can really be any kind of DC load as long as the working load voltage is  <= 30VDC and the load current is < 2A continuous. It could be as small as a LED indicator lamp, a solenoid valve, the coil of a 12 or 24V relay or contactor, or a DC motor.

Output Driver Voltage Current OFF Internally pulled up to V+ via a 20K ohm resistor Leakage < 0.1mA ON < 0.3V 4A peak, 2A continuos

Notes:

1. The maximum output load current for Ouput #1 to #6 on Wx-TERM16 is higher than that specified on the Wx100 or Wx-TERM8. This is because Wx-TERM16 added high current output buffer driver to drive all outputs #1 to #14.
2. All digital outputs are directly programmable in Ladder Logic as well as in TBASIC custom functions. Some programming examples are detailed in the “Wx100 PLC’s User Manual – Chapter 3 – Programming The I/Os“

 

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Wx-TERM16 adds 4 channels of 12-bit analog outputs to Wx100.  DAC #1 and DAC#2 are 0-20mA current output,  while DAC #3 and DAC #4 are 0-5V voltage output.

Specifications

• All 4 analog outputs are current sourcing types, meaning that analog currents flow out from the analog outputs into the load and return to the Wx-TERM16 0V terminal as shown in the wiring diagram below.
• For the two channels of 0-20mA current loop analog outputs (DAC #1 and DAC #2), the compliance voltage (i.e. the maximum output voltage that will be presented to the load)  is typically about 1V less than the power supply input voltage (V+) to the Wx-TERM16.
• The two channels of 0-5V analog outputs (DAC#3 and DAC#4) are unbuffered and can only deliver <= 1mA current per channel.  You will be able to connect directly to analog equipment that features high impedance analog input. Additionally, it is possible to convert these two analog outputs also to 0-20mA current loop outputs using an analog current converter such as the AN20MA-2.

 

Converting 0-20mA Analog Outputs(DAC1 and DAC2) to Voltage Output

The main advantage of 0-20mA current loop output is that it is ideal for controlling analog equipment located far away from the controller. This is because the current loop driver automatically raises the output voltage to compensate for the unavoidable resistive voltage loss develop across a long connecting cable due to resistance in the connecting wires in order to main a constant current output based on the analog output value regardless of the length of the connecting cable.

If the remote equipment requires a voltage input instead of a current input, then you simply connect a load resistor at the analog input of the remotely located equipment to convert 0-20mA to voltage output. For example, to convert the current loop to 0-5V, use a load resistor of 250 ohms (easily formed by a 120 ohm resistor in series with 130 ohm resistor). To convert the current loop to 0-10V, use a 500 ohm resistor, as illustrated in the following figure:

   Example 1:   SETDAC 1, 2000

   Example 2: SETDAC 4,1000

     x = (Expected output/Measured output - 1)*10000

     x = (10.0/10.025 - 1)*10000 = -25