2/24/2016 8:15 AM | |
Posts: 10 Rating: (0) |
Please Help anyone |
2/24/2016 8:45 AM | |
Posts: 5225 Rating: (1192) |
My friend Duris told me the other day (smile) |
2/24/2016 9:24 AM | |
Joined: 4/28/2015 Last visit: 2/7/2024 Posts: 10533 Rating: (820) |
Hello, hope this will be helpfull to you Ygor simply set correct HW module ID. You can also put correct HW address to Port via click on that Port, then you can have prepared that PORT as parameter, but you must correctly set value. Update: but better help will be William's pictures with arrows (red/blue) showing exactly needed steps AttachmentMB_cfg.zip (575 Downloads) |
Last edited by: Duris_I at: 2/24/2016 9:33:19 AMWith best regards... |
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2/24/2016 8:48 PM | |
Posts: 10 Rating: (0) |
Hi Here are some screenshots of the code. As i said before I want to read three current measurement from the Relay. According to SEL 751A Relay manual appendix E Table E.34 the User Map Register Values are in registers 126 to 250. Also according to S7-1200 manual Table 12- 69 Modbus functions, if I use MODE zero I should be able to read the Read Holding registers 40001 to 49999. That is why in my code i made it so it reads the first 3 values on the Relay. For The Master REQ I used a switch, to enable any time I want to read. But I keep getting a 8180 Invalid port ID value ERROR on the Master. Not sure if my Code is totally wrong or the Relay itself is not communicating. Thanks
Today I used ModScan64 to see in the Relay could communicate with My PC and it did. At first I was worry that my logic on the Relay was wrong. But given that it work with ModScan64 (I was able to Read and write to it). I am almost certain that something is wrong with my code. I am very new to PLC coding and please forgive me for my simple questions. Thank you again Duris_I and William_B for the support. I am not getting a 8180 Invalid port ID on the MB_COMMNDLOAD anymore. But my MASTER block is still given the 8180 error. Do I need to add more to my code? |
Last edited by: Ygor0191 at: 2/25/2016 3:36:49 AM |
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This contribution was helpful to1 thankful Users |
2/29/2016 4:03 AM | |
Posts: 10 Rating: (0) |
Hi William_B What do you mean by "Do consider putting an auxilary flag in to trigger the load function (in parallel) with the first scan bit." Thank you |
3/7/2016 4:03 AM | |
Posts: 10 Rating: (0) |
Hi William_B Attached is the last version of my code. I followed your advice, but it did not work :( I am a little frustrated, I know that the SEL 751A relay works via modbus because I tested it with modScan64 software on my computer. The comm load block runs with no error, but the Master block is still given me that 8081 invalid port id error. I made sure I inputted the correct slave ID, check the Rs232 cable, and to me my code made sense, I should be able to read. One interesting finding is that the CM1241 rs2323 communication module on the PLC, Tx and Rx LED do not blink at all when I run the program. I have consulted with a professor at my university and he did not know how to help me. thank you again for your support Hope to hear from you soon. Regards Ygor AttachmentModbus code.zip (347 Downloads) |
3/7/2016 7:55 AM | |
Posts: 10 Rating: (0) |
Hi william_B What do you mean by "review x3 pins hidden from view on the MASTER instruction" I have look over the master block and Cant seem to find the hidden pins? Could you clarify this for me? On another note: I was looking into the S7-1200 manual the section 12.3.5.1 Configuring the communication module. In this example, an S7-1200 CPU communicates to a PC with a terminal emulator through a CM 1241 RS232 module. I have come to realize that I never did any configuration of the CM1241. All I did was detect the modules attached to the PLC, then look up the hardware ID for the module and make the COMM and MASTER blocks respectively. My question know is do I need to Program the PtP communications before using Modbus rtu communication? configure the PORT_CFG. SEND_CFG AND RCV_CFG blocks? because if so, that might be my issue. I have attached the section of the manual so you can refer to what I have said. A thousand thanks for following up to my questions. Attachmentmanuel-plc-siemens-s7-en.pdf (406 Downloads) |
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