--- title: "Aimoxun Amsamotion Modbus TCP evaluation and connection ETH-MODBUS-IO8R-A" url: "https://maker.wiznet.io/teddy/resellers/aimoxun-amsamotion-modbus-tcp-evaluation-and-connection-eth-modbus-io8r-a/" markdown_url: "https://maker.wiznet.io/teddy/resellers/aimoxun-amsamotion-modbus-tcp-evaluation-and-connection-eth-modbus-io8r-a/md" type: "VAR: Value-Added Reseller Products" author: "Aimoxun" author_url: "https://www.codeaw.com/archives/429#respond" editor: "WIZnet" editor_url: "https://maker.wiznet.io/" original_author: "Aimoxun" original_url: "https://www.codeaw.com/archives/429#respond" published: "2022-12-27" language: "en" likes: 1 views: 704 comments: 1 source: "WIZnet Makers (https://maker.wiznet.io/)" --- # Aimoxun Amsamotion Modbus TCP evaluation and connection ETH-MODBUS-IO8R-A > Aimoxun Amsamotion Modbus TCP evaluation and connection ETH-MODBUS-IO8R-A Original author: Aimoxun (source: https://www.codeaw.com/archives/429#respond) ## Article ### Aimoxun Amsamotion Modbus TCP evaluation and connection Aimoxun ETH-MODBUS-IO8R-A is an affordable Modbus TCP IO module ### 1 Introduction:   First of all, let me declare that we have no cooperation or conflict of interest with Aimoxun. We think it is well planned and the price is also very good. Let me share it here.   Although we recommend using EtherCAT IO modules for ease of use and real-time performance, and using high-side smart switch chips to replace transistors and relays, the price of Aimoxun is too low, and it is very difficult to use in the low-end market and low-demand markets. Have requests.   Normally, using our custom EtherCAT IO module for the core board, taking digital 16 inputs and 16 outputs and analog 4 inputs and 4 outputs as an example, the minimum cost is about 430 yuan. It is roughly estimated that 8 inputs, 8 outputs, 6 analog inputs and 1 analog output should be more than 330. However, Aimoxun's ETH-MODBUS-IO8R-A can be priced within 300, and the 5 input and 5 output pure digital can be achieved within 200. I have to say that cost control is very powerful.   Although the price is low, we found that the material and workmanship are not bad after dismantling, which is at the upper-middle level. Some protections are not in place, but most applications can be satisfied.   You can [find relevant information](http://www.amsamotion.com/product_view_993_388.html)[here](https://item.taobao.com/item.htm?id=620500024972) and buy it here . ### 2. Disassembly: Outer packing: ![](https://i0.wp.com/www.codeaw.com/wp-content/uploads/2021/01/Amsamotion_1.jpg?w=3840&ssl=1) The shell is not bad in workmanship. At first glance, you may think it is a Siemens product. ![](https://i2.wp.com/www.codeaw.com/wp-content/uploads/2021/01/Amsamotion_2.jpg?w=3840&ssl=1) ![](https://i1.wp.com/www.codeaw.com/wp-content/uploads/2021/01/Amsamotion_3.jpg?w=3840&ssl=1) The interior consists of two double-layer PCBs, the upper layer is the core board, and the lower layer is the IO board. The single-chip microcomputer is STM32F103, which is equipped with W5500 to realize the Modbus TCP function. ![](https://i2.wp.com/www.codeaw.com/wp-content/uploads/2021/01/Amsamotion_4.jpg?w=3840&ssl=1) ![](https://i2.wp.com/www.codeaw.com/wp-content/uploads/2021/01/Amsamotion_5.jpg?w=3840&ssl=1) On the lower IO board, the digital input is isolated by optocoupler, the digital output is driven by a Darlington tube, the analog input is divided by resistors, and the analog output is amplified by an op amp. It is a relatively standard design. The layout is acceptable, except for a capacitor on the right interfering with the upper plug-in, there is no major problem. ![](https://i0.wp.com/www.codeaw.com/wp-content/uploads/2021/01/Amsamotion_6.jpg?w=3840&ssl=1) ![](https://i0.wp.com/www.codeaw.com/wp-content/uploads/2021/01/Amsamotion_7.jpg?w=3840&ssl=1) ### 3. Connection with Codepi (CoDeSys) After consulting the user manual, it is known that the module uses Modbus TCP to RTU to communicate, not direct TCP communication. So we do the topology as shown below: ![](https://i0.wp.com/www.codeaw.com/wp-content/uploads/2021/01/Amsamotion_8.jpg?w=3840&ssl=1) The specific steps are: 1. First add an Ethernet device, which is the bottom for modbus tcp. 2. Add Modbus TCP Master under Ethernet, and use PLC as the Modbus master station. 3. Add Modbus TCP Slave under Modbus TCP Master, that is, add a slave station. If it is a standard modbus tcp device, stop here. But Aimoxun uses the TCP to RTU solution, so we have to add another step. 4. Add Modbus Slave COM Port under Modbus TCP Slave, which is the actual slave station, corresponding to the dialer address. 5. Add the corresponding address in Channel, use function code 2 to read digital input, and function code 15 to write digital output. Other reference manuals. ### 4. Summary At present, Aimoxun has launched two modbus tcp modules, namely [ETH-MODBUS-IO8R-A](http://www.amsamotion.com/product_view_993_388.html) and [ETH-MODBUS-IO5R](http://www.amsamotion.com/product_view_917_385.html) . The details are handled quite well. The output will be turned off after a communication interruption of about 2 seconds, and the w5500 will be reset when the power is turned on. After repeated tests, there is no problem. **Due to the adoption of the Modbus TCP to RTU mode, the onboard COM1 can be directly connected to the next slave station** , and the IO device of other Modbus RTU can be connected by modifying the address of the slave station. As shown below: ![](https://i2.wp.com/www.codeaw.com/wp-content/uploads/2021/01/Amsamotion_13.jpg?w=3840&ssl=1) I don't have any redundant Modbus RTU slaves to test, so I use an oscilloscope to grab a waveform. ![](https://i0.wp.com/www.codeaw.com/wp-content/uploads/2021/01/Amsamotion_15.jpg?w=3840&ssl=1) (The modbus decoding of ps6 requires 2-bit stop or 1-bit parity and 1-bit stop, so the UART decoding is correct (1-bit stop, no parity), but the Modbus RTU decoding will be wrong. This parameter can be modified on the host computer debugging tool or on the webpage ) In this way, more devices can be connected, such as 16-in 16-out transistor type, analog input and output, etc., without considering the stability, isolation performance and serial port address of USB to RTU, which greatly facilitates Modbus IO connection and debug. --- Source: https://maker.wiznet.io/teddy/resellers/aimoxun-amsamotion-modbus-tcp-evaluation-and-connection-eth-modbus-io8r-a/