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Modbus TCP Comm. with WinLC RTX

Created by: AhmetTan at: 9/7/2010 9:54 PM (8 Replies)

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9/7/2010 9:54 PM	Rate (0)
AhmetTan Experienced Member Joined: 3/17/2010 Last visit: 11/10/2023 Posts: 29 Rating: (0)	Hello, I read many threads in this forum to learn how to establish a Modbus TCP with a PN CPU. Finally I downloaded the demo package of "S7 - OPEN MODBUS / TCP Communication via the integrated PN interface of the PLC" and installed it. I also downloaded the Modbus TCP Wizard. After all configuration I downloaded the example project and all blocks to the CPU. Now, SF flash is blinking. I have checked the diagnostic buffer, it shows an Event ID 16#A090 and "Area length error". I have attached the screen capture of those errors. When I checked the documentation of Modbus TCP package, It says "When the registration key is missing or a wrong one is detected, the SF LED (S7-300 and IM151-8) or the INTF LED (S7-400) of the CPU is flashing. A cyclic error message regarding the missing license is displayed in the diagnostic buffer too. The error number of the missing license is W#16#A090" However, it also indicates that "Modbus communication is carried out even with a missing or wrong registration key, but the output STATUS_MODBUS is set to W#16#A090 “no valid license”. I expect that it should work. Example project itself -without making any change or adition- should establish some data transfer. Am I right? My system is S7-mEc EC31-RTX. I am trying to use it as a client. Other side is Mod_RsSim simulation software acting as a Modbus server. Simulator software doesn't get any data from CPU right now. When I monitor DB102 Instance data block, "MOD_CLI.TCP_COMM..SEND.ERROR" is true. What am I doing wrong. Is it a license issue? or anything else? Any suggestion? Thanks Ahmet Attachment WinLC_Module_Info.JPG (722 Downloads)

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9/7/2010 10:10 PM	Rate (0)
Kaulquappe Posts: 3093 Rating: (323)	Hello Ahmet, when you get the error bit, an error has occurred. The error number in STATUS is displayed dynamically - it is valid for one cycle. The message A090 - missing license- is set without error bit. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (323)
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This contribution was helpful to 1 thankful Users AhmetTan

9/7/2010 10:44 PM	Rate (0)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 11/7/2024 Posts: 12293 Rating: (2691)	Hello AhmetTan; There are 2 issues I can see here: First, with the demo software of Open Modbus TCP, the SF LED will keep blinking until the license is installed (see Weustenraeuber's posts in the foolowing thread); but communications will work if properly configured, as Kaulquappe has pointed out. /tf/WW/en/Posts/47318 Second, an "Area length error" error message means that you are trying to reach an address that doesn't exist, that has not been configured or that cannot be reached at the present time. So check your porgram, there has to be an addressing error somewhere. Hope this helps, Daniel Chartier
	Last edited by: dchartier at: 9/7/2010 10:46 PM Last edited by: dchartier at: 9/7/2010 10:45 PM
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This contribution was helpful to 1 thankful Users AhmetTan

9/7/2010 11:28 PM	Rate (0)
Kaulquappe Posts: 3093 Rating: (323)	Hello dchartier, the Modbus blocks force an unvalid access to force the diagnostic entry A090. The additional entry of the wrong length is no error in the users program. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (323)
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This contribution was helpful to 2 thankful Users dchartier JordyDG

9/8/2010 1:11 AM	Rate (0)
AhmetTan Experienced Member Joined: 3/17/2010 Last visit: 11/10/2023 Posts: 29 Rating: (0)	Thank you for the clarification and help. I have a few other issues. 1- After I read your replies, I tried to find out the problem in the example software. When I diagnose DB1 online, I saw that RECV_TIME and CONN_TIME was 0. and CONN_ESTABLISHED was true. Initial value for those is 50ms and 120ms, and in OB100 they set for 500ms and 5s. I don't know where they were reset to 0ms. I set them up to 500ms and 5s in OB121. In that case, it worked. I could communicate to simulator. At the manual, it says: "The block MODBUSPN must be called in OB121 with the same instance DB as in the start-up OB and the cyclic OB." What that means? When I load the example project to my system, OB121 was empty. Now, there is only RECV_TIME and CONN_TIME set values in it. L 500 T "CONTROL_DAT".RECV_TIME L T#5S T "CONTROL_DAT".CONN_TIME Do I need to copy the content of OB100 or OB1 to OB121? I believe, because I have no license yet, Program gives an error and call OB121. So MODBUSPN should run in OB121. Am I right? 2- I said above, "in that case it worked". But not properly.DB2 has set to read two sets of holding registers, some input registers and coils... etc. Right now I am reading only 1 byte of data from Holding Register 1. Is it related to the problem in 1 above? 3- My CPU is S7-mEC (modular embedded controller) WinLC RTX (EC31). At the Modbus TCP Wizard, there is not such a CPU. I chose IM151-8, WinAC IF1. Is it the best option that I can choose? Thank you.

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9/8/2010 7:51 PM	Rate (0)
AhmetTan Experienced Member Joined: 3/17/2010 Last visit: 11/10/2023 Posts: 29 Rating: (0)	I still work on this Modbus TCP problem, and something is still not right. In DB2 (modbus_param), I have only one data area to read. I am trying to read a set of holding register starting address is 1 and end address is 100. In that case I read only 1 byte of holding register 1 instead of 100 register. What is the problem? (Please consider everything with my previous message) When I change the starting address from 1 to 2 (start address=2, end address=100) software returns with an error. STATUS_MODBUS returns A006. A006 is "The given range of registers defined with DATA_TYPE, START_ADDRESS and LENGTH does not exist in data_type_1 to data_type_8." In that case I am still connected to simulator. (CONN_ESTABLISHED is true) When I check out DB2, everything looks great. What am I missing? Thanks

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9/9/2010 4:23 PM	Rate (0)
Kaulquappe Posts: 3093 Rating: (323)	Hello Ahmet, when you set START_1 = 1 and END_1 = 100 the register numbers from 1 to 100 are mapped. When you read START_ADDRESS=2 and LENGTH=100 the register numbers from 2 to 101 should be read. In that case error A006 is the result as register 101 is not mapped. I do not believe that you can only read one byte when using START_ADDRESS=1 and LENGTH=100. Do you get the bit DONE after this job? If yes, all read data are transferredto the receive DB. Just write FF to the receive DB to see whether 00 is the received data. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (323)
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9/9/2010 6:05 PM	Rate (0)
AhmetTan Experienced Member Joined: 3/17/2010 Last visit: 11/10/2023 Posts: 29 Rating: (0)	Kaulquappe, Thanks for the reply. My register data in the simulator is different than 00. Simuator gets the command read 1 from 1. and only send first register. It doesn't get all the rest 99 registers. I am using Modbus TCP Wizard, and enter 1 for START ADDRESS and 100 for END ADDRESS. Wizard doesn't ask me any Length info. After wizard creates the DB2 (Modbus_Param) datablock, I check it, and confirm the addresses I entered are in the right place. But when I download the program, it doesn't run with that data. Program should read data area_1 (data type_1, db_1, start_1, end_1) and prepare the correct data for DB1. When I looked at DB1, START ADDRESS = 1 and LENGTH = 1. I don't know where DB1 gets this data from. When I entered start_1 = 2 and end_1 = 10 in DB2, again DB1 gets the same data,START ADDRESS = 1 and LENGTH = 1. Another strange problem in DB1 is timing data. In OB100, RECV_TIME an CONN_TIME is set for 500ms and 5s. However DB1 set them for 0 and 0. I set them again to 500ms and 5s at the beginning of OB1. Otherwise program doesn't run. I am using S7-mEC PLC. I don't know if it is related to that CPU since it is not listed as supported CPU list. I'll check the same program with 315 PN/DP. Any comment or advice to the problem I mentioned? Thanks
	Last edited by: AhmetTan at: 9/9/2010 6:07 PM
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9/14/2010 11:46 AM	Rate (0)
Wüstenräuber Gold Expert Joined: 10/3/2008 Last visit: 8/28/2024 Posts: 961 Rating: (124)	Hi, the parameters in the wizard are not the runtime parameters, these are the initialization parameters! In wizard you say, which registers are mapped into which DBs. The entries in wizard don't start any modbus telegram. At runtime you say with DATA_TYPE, START_ADDRESS, LENGTH etc. which registers you want to read or write with the current order. These parameters you have to set in your program (or in a VAT). Wüstenräuber

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