9/3/2011 12:36 PM | |
Posts: 45 Rating: (1) |
Dear experts, I have purchased OpenModbus TCP Redundant ( 2XV9450-1MB01) since i am going to establish a modbus TCP connection between two 417-H systems. I have studied the relevant manual but there are some points unclear to me please help. 1- In the sample project, data blocks related to register areas are the same for both server and client. There is no DB dedicated for SEND and RCV. It is not clarified which DB should be considered as SOURCE DB and which as DESTINATION. I mean, if the Client reads some registers of Server, in which DB(s) are the results saved? 2- Is it true to consider the Client equivalent to Master in RTU communication? 3- In the sample project's NetPro, an "Other station" is inserted and configured as Server. As i have two 417-H AS, one of these two should play the Other station's role OK? 4- In RTU system we were used to develop a sequential function for Modbus Master to pole each slave respectively. In TCP mode, is there any CFC needed other than the one which contains MODB4H FB? 5- In Open Modbus Manual it is said: "DB_1 to DB_5 are used for the Holding Register, DB_6 to DB_8 are used for the Input Register". What does "Holding Register" mean? As we know FC3 reads output registers, FC4 reads Input registers and FC16 presets multiple registers. 6- How the " write-read " input of MODB4H block should be parameterized for Server and Client? Thanks in advance Splitted from Modbus TCP communication problem. |
Last edited by: O_Moderator at: 9/5/2011 8:37 AMnew subject after splitting |
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9/7/2011 3:39 PM | |
Posts: 45 Rating: (1) |
Thanks guys for the replies I am still confused with modbus TCP communication. As i said before, I have two H-Stations, One as SERVER and the other as CLIENT. I have attached my project sample here which the SERVER and CLIENT stations are inserted into a multiproject. (The archive zip file is splitted into 2 parts due to 3000 KB limitation of each post. The second part is attached in subsequent post. Please first unzip each file to get the splitted parts.) I have a dedicated CP443-1 for MODBUS-TCP for each H-station and I have configured the communication mode as double-sided (two TCP-connections per CP443-1). It seems all network connections are correct since all connections in NetPro shows the "established" status as it goes online. Please have a glance at my CFCs: 1- In Client's CFC, the MODB4H has a "R-TRIG" block for ENQ-ENR input (as illustrated in MODBUS_TCP sample project) but the R_TRIG block does not generate a contiguous pulse by itself, therefore i have built a 0.5Hz pulse generator (FB 1) using CPU clock memory. Is it OK? 2- I have parameterized DB_X, START_X, and END_X for DB1 and DB6 both in SERVER and CLIENT CFCs. Are the two parameters (Start_Address and Lenght) at the buttom of the block, related to those DBs or not? 3- Some parameters are told to be input in CLIENT and output in SERVER. Does it mean that it should not be parameterized in SERVER mode? 4- What is the "UNIT Identification" parameter at the most buttom of the block? There is no explaination in MODBUS_TCP Manual. 5- As i start module diagnostic for CP_0 or CP_1 in HW, the status shown is: "wait for sending data" and "wait for receiving data". the quantity of SND/RCV messages is 0. 6- The MODB4H block in Client's CFC returns error No: A083 which means that a new request is initiated before the previous one is done. 7- If a connention establishes without any error, a value change in Server's DB_X should result the same change in client's DB_X (in read mode) OK? Please HELP AttachmentMODBUS TCP-TEST-part1.zip (383 Downloads) |
9/7/2011 3:45 PM | |
Posts: 45 Rating: (1) |
Please unzip the attached file to get the second part
AttachmentMODBUS TCP-TEST-part2.zip (352 Downloads) |
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