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Control Techniques UD71

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Part NumberUD71
ManufacturerControl Techniques
TypeOption Modules
Warranty2 Year
RangeSerial communications
Category Large option module
ModesANSI, Output Input

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MRO Electric repairs CNCs, PLCs, Servo/Spindle Drives, Motors, Amplifiers, VFDs, HMIs, and more, most of which can be repaired in only 3-5 days.

Repair Benefits

MRO can restore your failed UD71 to remanufactured condition and save you up to 75% compared to buying new. We offer standard repair pricing to ensure you the best value for your repair.

Our certified technicians use rigorous testing procedures to ensure your parts are restored to fully functioning condition. Our team proudly stands behind all repairs by providing a minimum 2-year warranty.

Our technicians have vast experience with most manufacturers and models. In addition to this UD71 we also repair a wide range of other Control Techniques products, so if you don’t see the model you need, please contact us.

Core Exchange

If you are interested in getting credit for your faulty UD71, just let us know, and we can issue you an RMA to send it in as an exchange. Our exchange program provides you with savings and keeps us stocked for the next time you need anything.

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MRO Electric provides a 2-year warranty on every item we sell and repair. We stand behind all of our products and guarantee them for the full 2 years. If there is an issue with any of our products within the warranty period, we will evaluate the unit and repair or replace it under warranty.

Control Techniques UD71 Overview

Control Techniques UD71 Serial Communications

Discover the heart of communication in automation with Control Techniques UD71 Serial Communications. From installation to parameter intricacies, delve into UD71's role in seamless drive integration. 


Switch off the Unidrive and disconnect it from the supply for 15 minutes. Insert the Large Option Module, ensuring a correct connection. Utilize the appropriate connecting cable from Table 1 and connect it to the correct connector on the Large Option Module.

Hardware Connections:

Follow Table 1 for EIA RS485 communications port connections. The pin configurations for 4-wire and 2-wire modes are provided in detail.

Software Parameters:

Configure parameters such as Serial Address, Serial Mode, Baud Rate, Two Wire Mode, Serial Programmable Source/Destination, and Scale Factor. Understand the ranges and default settings for each parameter.

Serial Communications Modes:

Explore three modes: ANSI Mode, OUTPUT Mode, and INPUT Mode. ANSI Mode utilizes 4-wire EIA RS485 with the ANSI protocol. OUTPUT and INPUT Modes use high-speed binary protocols for continuous data transfer.

Parameter Description:

Understand parameters like Serial Address (11.23), Serial Mode (11.24), Baud Rate (11.25), Two Wire Mode (11.26), and Serial Programmable Source/Destination (11.27). Serial Scale Factor (11.28) allows data scaling in serial modes 1 or 2.

Control and Addressing:

Learn the addressing structure with Group Address and Unit Address. Control characters (EOT, ENQ, STX, etc.) facilitate drive communication. Group addressing enables commands to multiple units simultaneously.

Reading and Writing Data:

Reading involves sending structured messages and receiving corresponding data. Writing data requires a specific message structure, including Group Address, Unit Address, Menu, Parameter, Data, and Block Checksum. Understand the process of re-writing data for subsequent write messages.

Calculating Block Checksum (BCC):

Use the XOR function for BCC calculation. An example and QuickBasic program are provided for better understanding.

The Control Techniques UD71 Serial Communications guide offers detailed insights into installation, hardware connections, software parameters, communication modes, addressing, and data transmission. This ensures efficient utilization of the serial communications link for Unidrive systems.

FAQ - Control Techniques UD71 Serial Communications:

1. What is the purpose of the UD71 Serial Communications link?

  • The serial communications link enables the integration of one or more drives into systems controlled by a host unit, such as a PLC or computer.

2. How many devices can be connected in a single group using the EIA RS485 standard?

  • In two-wire mode, up to seven drives can be connected in a single group, and up to 15 drives if the four-wire mode is used.

3. What are the hardware connections for the EIA RS485 communications port?

  • Refer to Table 1 for detailed hardware connections, including pin configurations for 4-wire and 2-wire modes.

4. What parameters are essential for configuring the serial communications link?

  • Parameters such as Serial Address, Serial Mode, Baud Rate, Two Wire Mode, Serial Programmable Source/Destination, and Scale Factor play a crucial role in configuration.

5. How does group addressing work in UD71 Serial Communications?

  • Each drive on an ANSI communications bus is assigned a unique identity with a Group Address and Unit Address. Group addressing allows commands to be sent to all units of a specific group simultaneously.

6. Can data be transferred between drives using UD71 Serial Communications?

  • Yes, UD71 supports high-speed binary protocols in OUTPUT and INPUT Modes, facilitating data transfer between drives.

7. What is the purpose of the Block Checksum (BCC) in data transmission?

  • BCC is calculated to ensure the integrity of messages during transmission, preventing data corruption. It is essential for reliable communication.

8. How can I read and write data to UD71 parameters?

  • Reading involves sending structured messages, and writing requires a specific message structure, including Group Address, Unit Address, Menu, Parameter, Data, and Block Checksum.

9. Can I re-write data to a drive parameter without re-transmitting the address?

  • Yes, once a WRITE message with the address field has been accepted, subsequent write messages to that drive can use a re-write message structure, saving time during data monitoring.

10. Is there a limit to the number of devices that can be operated when using line buffers?

  • When line buffers are used, up to 81 devices can be operated, organized in up to 9 groups of 9. This allows flexible control without affecting other devices or groups.

These FAQs provide a quick reference for common queries related to UD71 Serial Communications, covering installation, configuration, data transfer, and addressing.Control Techniques products are manufactured in United Kingdom and are designed for Metal production, paper processing, and material conveying usage. They come with a 2-year warranty from MRO Electric. We also carry Option Modules from other manufacturers such as Siemens and Yaskawa.

Contact Us Today For More Information About Control Techniques Products

Check out the rest of our Control Techniques product line. Whether it's using our online instant quote feature, giving us a call at (800) 691-8511, or emailing us at, we strive for customer satisfaction first. This means lower prices and better service for you. For more products like UD71, take a look at more from our Option Modules line. If your current unit has gone bad, take advantage of our Core Exchange program for the most inexpensive route. You can learn more about this program on our FAQ page here. We offer a repair service on all of our UD71 products that keep your downtime to a minimum. To stay up to date on manufacturer news, as well as access any of our datasheets, manuals, or other documentation, we suggest you take a look at our blog.

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