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Product Data Sheet - I/O PLEXER

Remote I/O Controllers
from duTec provide
cost effective solutions
to real world process
control needs

Real world process control requires reliable analog and digital I/O. duTec's responsive technical support minimizes the hassle and cost of system design, trouble shooting, and successful operation.

The I/O PLEXER is a complete, industrial-grade, remote I/O controller which can operate under the control of a host computer via a serial communications link, or in a STANDALONE mode, with or without supervision. By locating I/O PLEXERs near the process, the serial link eliminates the expense of lengthy, noise-prone analog sensor and actuator field wiring. Because the I/O PLEXER supports any mix of a large variety of analog and digital I/O signals, the requirements of virtually any process can be accommodated. Omni-isolated I/O modules provide 1,500 volts of isolation protection between each and every I/O line, host computer and power supplies.

Omni-isolated I/O, and the ability to mix and match individual analog or digital signals* from virtually any sensor or actuator reduces system design, installation and trouble shooting costs, as well as simplifying future maintenance and system expansion. I/O PLEXERs, complete with a built-in wide range power supply, are shipped ready to connect to your sensors, actuators, host's serial port and power. A single I/O PLEXER can handle any mix of 16 analog and/or digital I/O points. With expanders, the number of digital I/O points can be increased by up to 48. An I/O PLEXER network can serve a mix of over 1,000 analog and digital I/O lines.

The host computer uses RS-232 or RS-422/485 to communicate with I/O PLEXERs spaced up to 4,000 feet apart. Using telephone or radio modems, the distance is virtually unlimited.

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Remote Operation

There are several dozen third-party HMI/MMI/SCADA software packages that have I/O PLEXER drivers for polling sensor data. Most have extensive graphics displaying the process, only a few have the capability to transmit control commands to actuators. The open architecture communication protocol instructions are readily available for those writing their own proprietary software.

duTec's universal DDE driver can be used with all Windows® DDE compliant software packages. This includes most HMI/MMI/SCADA packages as well as Visual BASIC ® , spread sheets such as Excel® and numerous other programs. In addition to working with polling software packages, which use a speak-only-when-spoken-to communications protocol, the duTec DDE Driver allows a remote I/O PLEXER to initiate a scan when it detects user specified events. This Speak-On-Event (SOE) capability materially reduces the need for host initiated scans and communications circuit traffic, and in large networks reduces the time to detect problems. While the duTec DDE Driver has minimal graphics, it has a screen for the user to monitor and control the state or values of all analog and digital I/O points. It is particularly useful during system trouble shooting as it makes it possible to verify that the hardware is operating correctly before the application software is exercised.


Built-in LCFs (Local Control Functions) allow an I/O PLEXER to perform control operations with or without host supervision. LCFs include logic gates, analog compare and math, dead-band and PID control, and ladder logic. Because analog and digital modules are available on the same unit, LCFs can perform closed-loop control operations.

LCFs not only provide for faster, more predictable real-time response, but they allow an I/O PLEXER to assume control in the event of communications or host computer failure. The process continues to operate safely!

The unit can also be programmed to override an operator command which would result in an unsafe condition.

LCFs often eliminate the need for more expensive auxiliary hardware. Because LCFs can perform simple control tasks, the host computer needs to transmit fewer instructions, thus allowing both the computer and the network to serve higher-priority tasks. After LCF configurations are developed using duTec's Windows LCF Program Generator, they are down loaded and stored in the I/O PLEXERs EEPROM.

LCFs have virtual analog input and output "modules" which provide the means for the host to send and receive data without using an actual module position. The transfer of PID set point values to a remote unit is a common use for virtual analog "modules".

* See duTec's I/O Module Data Sheet for complete specifications


No jumpers are needed to configure an I/O PLEXER communications network address or baud rate, instead they are selected during initial setup via a single push-button, or remotely via the RS-232 port. Configuration information is saved in an EEPROM and is continually displayed to make it easy to verify the settings.

Data Integrity

Each command issued by the host includes a checksum. If the checksum calculated at the remote unit fails to match, the command is ignored and error message is returned. When the checksum matches, the command is executed and an acknowledgment is returned.

A built-in hardware watchdog timers ensure safety by responding to both communications or hardware failures. If the communications watchdog time out occurs, both analog and digital outputs can be programmed to specified values. Should there be an I/O PLEXER failure, all outputs are returned to an OFF state. Each time the unit is powered up, built-in diagnostics test system operation and display any detected faults.

Trouble shooting

Receive and transmit indicators provide a means for verifying the communications circuit operation. The use of only ASCII printing characters in the communications protocol provides a means of observing what is actually being transmitted and received.

With the included Magic program disc, individual I/O points can be operated making it possible to verify wiring, and sensor and actuator operation before the application software is started.

In addition, duTec's readily available technical support helps to ensure worry-free installation, operation and product satisfaction. Several utility programs and, DDE and LCF demonstration software are available here.

Plug-in Connections

Should a unit need to be replaced, downtime can be minimized, by unplugging the 16 I/O point field wiring terminal block. In addition both the RS-232 and RS-422/485 connectors can be unplugged.

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Operational Functions
Analog (12 bit resolution) Digital
Inputs   Outputs Inputs Outputs
Signal levels
Set Levels
Read input state Set output state
Linearized temperature
& RTDs
Square waves
Periods: 100mSec
to 10.9 min.
Count pulses
Up to 65,535
Up to 500 Hz
One-shot pulses
Durations up to 655Sec
Up to 10KHz

Pulse durations
Single or multiple pulses
10 mSec resolution
Pulse trains
1-65,535 pulses
Sample & Hold
Max and mins
Up to 500Hz
Square waves Continuous
Periods: 2mSec-5Sec
Calculate averages
Up to 65,535 samples
Contact de-bounce
Periods up to 255mSec
Delay ON / Delay OFF
Periods: 10mSec - 655Sec
Detect Out-of- Range
high or low
Edge detection
1mSec acquisition time
Local Control Functions
AND/NAND OR/NOR Analog Compare Analog Math
2-input AND, NAND
3-input AND, NAND
4-input AND, NAND
2-input OR, NOR
3-input OR, NOR
4-input OR, NOR
2-input XOR, XNOR
A < B
A > B
A = B
A <= B
A => B
A <> B
A + B
A - B
Avg A and B
Max of A or B
Min of A or B
Latch State Machine Controllers Ladder Logic
Digital latch
D-Flip Flop
Analog sample & hold
Analog gate
Truth table
Alternate High Low
Time proportional/ PWM

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(click here for information regarding our Ethernet option)
Link Host to first I/O PLEXER Network
Standard RS-232 RS-422/485 RS-422/485
Type DCE Multidrop or repeater Multidrop or repeater
Range Host to first IOP 50' 4,000'
Multidrop 4,000' Total
Repeater 4,000' unit-to-unit
Handshake None or RTS/CTS None None
Data Format 10 bit ASCII 1 start, 1 stop, 8 data, no parity
Data Integrity Message checksum or message checksum plus 4-pass mode
Baud Rate 300-600-1200-2400-4800-9600-19,200-38,400
Wiring 3 wire, 5 wire with RTS/CTS
Dual twisted pair + secondary ground + AWG 18 or 30 solid, stranded or flexible
Connections DB9F Terminal block

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Scanning Rate

Communication baud rate and the mix of analog and digital I/O modules determines the speed  with which an I/O PLEXER can provide data to a host computer. The table below summarizes maximum performance when operating at a baud rate of 38,400.
Digital only I/O modules

1,600 points/Sec

Analog only I/O modules

640 points/Sec

Analog and Digital I/O modules

500 points/Sec

The host operating system and application program limit the rate at which the host can request data. These delays are often more significant than the baud rate.

Physical Specifications

Power (standard) 90-264 Vac, 47-440Hz, 30 watts; 3.0A fuse; (optional: 9-18Vdc and 18-36Vdc, 25 watts each)
Operating Temperature 0-60o C
Package 4 pounds, stainless steel
Humidity 95% non-condensing
Envelope 17.25"L x 5"W x 3.5"H (overall)

ioplexer line drawing

Figure 1: Outline drawings for I/O PLEXER, I/O PLEXER Repeater, and Digital Expander.
Dimensions follow.















Ordering Information

Model Number Description
IOP-AD 16 sockets for any mix of analog and digital modules
IOP-D 16 sockets for digital modules only

Option Codes

Description of I/O Controller Options


Controller logic & connectors for adding up to 3 IOP-DE, 16 I/O digital expanders


Expansion chassis with sockets for 16 digital only I/O modules, no power supply required;
prerequisite is /3+ option above


Alternate power supply for operation from 9-18Vdc @ 33W


Alternate power supply for operation from 18-36Vdc @ 33W

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