Greetings, I’m a senior college student carrying out a key engineering project involving an Allen-Bradley L16ER PLC. My current challenge lies in establishing communication between the PLC and an AutomationDirect STP-DRV-4850 stepper motor driver. The PLC solely supports ethernet connectivity, whereas the stepper driver operates via RS232 or 485 serial protocols. To bridge this gap, I acquired a USR-TCP232-306 ethernet to serial converter. However, RSLinx Classic Lite fails to recognize the converter, displaying a yellow question mark instead. If anyone can offer guidance on making the converter operational or suggest an alternative method for facilitating communication between the PLC and stepper driver, your input would be highly appreciated. It’s worth noting that I’m operating on a tight budget, ruling out the purchase of the official Allen-Bradley serial expansion card. Thank you in advance for your assistance!
The STP-DRV-4850's port protocols (SCL, ASCII) may pose a challenge. To enable communication between the two, consider using a protocol converter that can bridge ethernet and serial connections, such as the RTA 435NBX. This ASCII to Allen-Bradley PLC converter from RTA Automation is ideal for integrating barcode readers, weigh scales, and displays. To establish communication with the converter, RSLinx is not required. Instead, you will need to utilize raw sockets for communication, ensuring your controller supports this feature. If needed, seek guidance on AB Generic string communication through platforms like PLC Talk. For controlling the PLC, connect the necessary command signals based on your specific application requirements.
Working with a limited budget for hardware can be a challenge, but the inclusion of labor in the training budget may help balance things out. Before diving in, it's important to clearly define the problem at hand. As the saying goes, "a problem well stated is a problem half solved", and this rings true for many obstacles we face. Are you looking to control the motor controller with "step and direction" pulses? Or perhaps you intend to provide a target position via serial communication, along with a command to initiate the movement? Another option could be sending a direction and speed, followed by Start and Stop commands. The USR-TCP232-306 is a reasonably priced and well-industrialized TCP/IP to Serial server. Identifying its likely OEM was a task in itself, leading to the discovery of a Chinese industrial electronics provider known as PUSR. This device does not come with firmware that supports the Rockwell "EtherNet/IP" protocol and object model, but it does offer some Modbus serial-to-TCP conversion capabilities. However, it lacks compatibility with ControlLogix ASCII interfaces like the 1734-232ASC or products from Digi, Red Lion, Hilscher, HMS, RTA, or Spectrum Controls. Engaging in "Open Socket" communications with the CompactLogix system can be complex, especially for beginners. As an expert, I tend to opt for specialized devices when possible instead of delving into this method. Nevertheless, for your situation, it could be the feasible solution that aligns with your budget and hardware. To start off, determine the volume of data to be transferred, its communication protocol or format, and whether it needs to be bidirectional or simply one-way.
When controlling a stepper motor with a small PLC like the CompactLogix L16, the typical method is using step-and-direction. However, the built-in I/O of the L16 is not configured for high-speed pulse series control, unlike some other small PLCs such as the MicroLogix 1100/1400 and Micro 820/850/870. While the L16 is a great controller for basic CompactLogix applications, it may not be the best choice for fast I/O operations. For more advanced stepper motor control, AMCI offers specialized stepper control modules designed for the 1734 POINT I/O platform used by the L16/L18 for expansion I/O. If you're considering using the 1734-232ASC or -485ASC modules, keep in mind that they are optimized for sending ASCII string data with termination characters like carriage returns. If you decide to utilize the Ethernet/Serial converter, you will need to transmit data over Ethernet using the "open sockets" technique. To troubleshoot any issues, tools like Wireshark and RealTerm can be helpful for analyzing data from both ends.
The manual states that the stepper motor drive is compatible with both RS232 and RS485 protocols. The communication protocol (SCL) is structured as a text string followed by a carriage return (CR). Therefore, it is recommended to use 1734-232ASC (RS232) or 1735-485 (RS332 & RS485) for optimal performance.
Thank you, Tarik, for bringing up that point! I am currently exploring A-D stepper controllers and their communication protocols for a new project on my desk. I have been provided with a surplus 1769-L36ERM and 1769-ASCII and tasked with integrating them to control a group of existing Parker Compax3 servos via RS485 serial connection. This particular project has been at the forefront of my thoughts lately.
Hey there, You're in a tricky spot but it's not impossible to solve. While I'm not exactly familiar with your specific situation, in general when RSLinx has trouble recognizing devices it can be a driver issue. So, I'd suggest checking if you have the right driver installed for your converter. Alternatively, you may want to check if the converter itself has been configured correctly, as it might need to be set up to match the communication parameters of the devices it's bridging. Unfortunately, without the exact specs, it's a bit difficult to provide more specific advice. I'd recommend further investigating these potential issues, or possibly reaching out to the tech support of USR for assistance. Good luck with your project!
Hey there, I definitely understand your situation as I've had a similar experience myself. From my understanding, the yellow question mark usually appears in RSLinx when it doesn't recognize the device properly, which could be due to improper driver installation for the converter. Try re-installing the USR-TCP232-306 drivers and make sure they're the latest version. If RSLinx still doesn't recognize the converter, you might need to check the port settings in RSLinx. Ensuring it matches with the converter settings could solve the issue. Something else to consider is the MOXA NPort series of Ethernet to Serial adapters, which are known for good compatibility with Allen-Bradley PLCs. Hope this helps!
Hello, I've had a similar experience, but with different equipment. One solution might be to double check your RSLinx driver configuration. The USR-TCP232-306 converter might require a specific driver to be recognized. If that doesn't work, another workaround could be using an intermediary device like a Raspberry Pi. With some Python scripting, you could facilitate communication between your Ethernet-only PLC and your RS232-step motor. This could be a cost-effective solution if you're on a tight budget. Hope this helps you out!
Hi there, I believe the issue might be related to the converter's configuration or compatibility with the RSLinx Classic Lite. I would recommend verifying if the converter's TCP/IP settings match those of your PLC. You should also check the baud rate, data bits, stop bits, and parity settings. It's important for them to match on both sides to achieve efficient communication. If that doesn't solve the issue, you might want to check if the converter is compatible with your current version of the RSLinx software. Another cost-effective method might be to try using a different ethernet to serial converter that's proven to work with Allen-Bradley devices and RSLinx. I know MOXA and Quatech make some pretty reliable products that are often used by many in our field. Hope this helps and good luck with your project!
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Answer: - You can bridge this gap by using an ethernet to serial converter, such as the USR-TCP232-306. However, ensure compatibility and troubleshoot any recognition issues with software like RSLinx Classic Lite.
Answer: - If you encounter this issue, try checking the configuration settings of the converter, ensuring proper network connectivity, and verifying compatibility with the software and hardware components.
Answer: - Yes, besides using an ethernet to serial converter, you can explore other cost-effective options like third-party serial communication modules or adapters that support the required protocols for communication between the PLC and stepper driver.
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