Frequently Asked Questions for S7-300（2）
21: Which settings will be retained when the CPU is fully reset?When the CPU is reset, the memory is not completely deleted. The entire main memory is completely removed, but the data is loaded in memory, and saved in Flash-EP
ROM memory card (MC) or micro memory card (MMC), all the data will be retained. In addition to loading memory, the timer (CPU 312 IFM
Except for) and diagnostic buffers are also retained. A CPU with an MPI interface or a combined MPI / DP interface retains the interface only before all reset
Current address and baud rate. On the other hand, another PROFIBUS address is also completely deleted and can no longer be accessed.
IMPORTANT: After resetting the PG / PC, communication with the CPU can only be established via the MPI or MPI / DP interface.
22: Why can not I access the CPU online via MPI?
If the MPI parameter has been changed on the CPU, check the hardware configuration. These values can be compared with the parameters under "Set PG / PC interface"
Compare to see if there is any inconsistency.
Or you can do this: Open a new project and create a new hardware configuration. In the MPI interface of the CPU for the address and transmission
Speed sets the respective values. Write the "empty" item to the memory card. Insert the memory card into the CPU and then reopen the CPU voltage that will be stored
The settings on the card are transferred to the CPU. The current settings of the MPI interface have now been delivered, and as such, as long as the interface is faulty,
Connection. This method is suitable for all S7-CPUs with memory card interfaces.
23: What is the purpose of the bug OB?
If a description of the error (see file 1) occurs, the corresponding OB is called and processed. If the OB is not loaded, the CPU goes to STOP
(Exception: OB70, 72, 7 3 and 81)
The S7-CPU can identify two types of errors:
1) sync error:
These errors are triggered during the processing of a particular operation and can be attributed to a particular part of the user program.
2) Asynchronous error:
These errors can not be attributed directly to the running program. These errors include errors in the priority class, errors in the automated system
Error (faulty module) or redundant error.
24: What "fault OBs" should be programmed in DP slave or CPU315- 2DP master station?
When configuring a CPU315-2DP station as a slave, the following OBs must be programmed in the STEP7 program to evaluate the distributed I / O type
Error message:
OB 82 Diagnostic interrupt OB, OB 86 Subframe failure OB, OB 122 I / O access error
1) Diagnostic OB82: If a module that supports diagnostics and has issued a diagnostic interrupt to it has identified an error, it is both an entry event
Also send a diagnostic interrupt request to the CPU for outgoing events. The operating system then calls OB82. In the OB82 own local variables package
Contains the logical base address of the defective module and 4 bytes of diagnostic data. If you have not programmed OB82, the CPU enters the "stop" mode. you
The diagnostic interrupt OB can be blocked or delayed and re-released via SFC 39-44.
2) Subframe failure OB86: If a DP master system or a distributed I / O station is identified to be faulty (both for incoming and outgoing)
), The operating system of the CPU calls OB 86. If there is no programming OB 86 but there is such a mistake, CPU will enter
"Stop" mode. You can block or delay OB86 and re-release it with SFC 39-42.
3) I / O access error OB122: An error occurred while accessing the data of a module, and the operating system of the CPU calls OB 122. For example, C
The PU recognizes a read error when accessing the data of a single module, and the operating system calls OB 122. The OB 122 is associated with the interrupt block
The same priority class runs. If the OB 122 is not programmed, the CPU is changed from "RUN" mode to "STOP" mode.
25: Why in some cases, the reserved area will be rewritten?
In the hardware configuration of STEP 7, several operand areas can be defined as "reserved areas". This can be done after power-down, even if there is no backup battery
The contents of these areas can still be maintained. If you define a block as a "reserved block" and it does not exist in the CPU or is only temporarily installed
Some of the contents of these areas will be overwritten. After the power is turned on / off, the rest will be found in the relevant area.
26: Why can not the contents of the flash card be loaded into the S7 300 CPU?
Your item is on a flash card. Now use it to load S7 300. But after the end of the load found in the CPU RA M is still empty. This question appears
The reason for the problem is that you can not handle the program, "wrong" organization block (for example, OB86 no DP interface). In re-setting and re-starting
After moving the CPU, RA M is still empty. The diagnostic buffer will prompt some information about this "can not load" block.
27: When the CPU315-2DP as a slave, the CPU315-2DP as the master station when the diagnostic address
When configuring a CPU315-2DP station, you use the S7 tool "H / W CONFIG" to assign the diagnostic address. If a failure occurs,
These diagnostic addresses are added to the variable "OB82_MDL_A DDR" of the diagnostic OB. You can analyze this variable in OB82 to make sure it's faulty
Station and make the appropriate response.
Here's an example of how to assign a diagnostic address:
Step 1: Configure the slave via CPU315-2DP and assign a diagnostic address, such as 422.
Step 2: Configure the master station via CPU315-2DP
Step 3: Link the configured slave to the master station and assign a diagnostic address, such as 1022.
28: Do you need to set up the DP slave interface for the S7-300 CPU before you can use it for routing?
If you use the CPU as I-Slave, and the CPU is also the role of S7 router, then please note the following:
The DP interface for the routed slave must be set to active. This can be done in HW Config: the attribute pair on the DP interface
Dialog box, the option "Commissioning / Test operation" or "Pr ogramming, status / modify ..." must be activated. Notes on these settings
The items can be found in the table below.
For S7 routing connections, there are four available connection resources - independent of any other connected resources. There is no connection resource or S7 with PG / OP
Basic communication.
If you have to establish a connection via a DP interface to a communication partner located on its rack (as in CP 343-1), also use a road
By connection. And for routing connections through the MPI interface with a communication partner located on its rack, since in this case
, Can directly reach the partner. Note: This does not apply to CPU 318.
29: Why does not there be any return value when using the internal run schedule of the S7-300 CPU?
When the CPU 312IFM to 316-2DP parameterize the system function blocks SFC2, SFC3 and SFC4, a run time table is specified for one
More than "B # 16 # 0" identifier, then the error will be required and the function can not be used. In this case, it will be lost at the "RETVAL" output of the block
The identifier "8080h".
Note: For these CPUs, only one timer is available. So you should only use the identifier "B # 16 # 0". In a cycle block (OB1, OB35)
The system function SFC2 "SET_RTM" must not be called, but it should be called in the restart OB (OB100). You can also trigger by external
Device to start the block. Otherwise, the block will always be reset to run the chronograph, which will never be counted.
30. S7 300 do double hot prepared to ask: consult prawn, S7 300 in addition to 318, 315 can do double hot standby? Give an example! A: The concept of hot standby is a CPU failure, another CPU immediately put in. Time difference in milliseconds. Two CPUs require time for strict synchronization. Backup with 315-2DP is actually implemented in software, and only one of the two CPUs performs a redundant backup program and the other skips the program to synchronize it. Requirements are not strict occasions. To implement the soft redundancy function also need to buy "SW-REDUNDA NCY" software package, the specific examples of the package have. 31. How to do the useless analog input Q: When using analog 6ES7 331-7KF00-0AB0, there is a group of which is useless, there is how the standby channel should be connected. Such as 4-20ma, 4-wire A: 1 four-wire current in a group of two channels can be connected in series, that is, the positive input of a signal connected to a positive pole, a channel of the negative side of the two-channel positive, the input signal of the negative side of the two-channel negative, This flow through the two channels, does not affect the channel group diagnostic function. 2 two-wire current in parallel with the input port of a 1.5-3.3k ohm resistor 3 - +5 v / - + 10v / thermocouple to the short channel 4-4V unused channels and the same group of channels in parallel. 5 A set of inputs is not disabled in the hardware configuration, hardware tuning is set to B, and then the input of each channel is shorted. 32. How to add password to the program Q: Please advise! To the block encryption A: In Step7, you can first open a piece, in the "file" select "Generate Source" or shortcut "Ctrl + T", pop up a screen, fill in "object name" such as "tt", then Press OK to confirm that another screen will pop up, the left is all the blocks in your program. If you need to protect which blocks, move the blocks to the right and exit all the blocks and then into the SIMATIC Manager. In the S7 Program Sources find the file tt, double-click tt open, in the fourth line by adding "Know_How _Protect", and then compile, save without error. FB1, FB2 will be protected, such as want to remove the protection, in tt removed "Know _How _Protect" compiler can save. Note: Do not lose or delete the source file
(Such as tt), otherwise the program is protected, the user can save to other directories, or Export Source to the hard disk, and then delete the source file, so that others can only see unprotected blocks. 33. DI module input frequency Q: Will the 3211BH020AA0 module, DI input frequency up to how much? There is no indication on the sample! A: depends on the signal module high level of establishment time, and the program scan cycle, the former time is fixed, can be ignored, the latter a greater impact, if a program's average scan cycle of 20 milliseconds, then enter The signal high and low time must be greater than 20 milliseconds, the input signal cycle is greater than 40 milliseconds, so the signal frequency is less than 25HZ, consider the scanning cycle changes in the factors that may enter the signal frequency is less than 15HZ can be reliably identified. Can not meet the above requirements, should use the SM321-7BH interrupt input module, the response frequency of up to 1000HZ. 34. OB100 Q: OB100 is a warm start function block, S7-300 CPU313C-2DP should only warm start, I OB100 in the preparation of the most simple procedures, namely: normally closed input M1.0 output M2.0. Why can not watch online. I understand that: after the start of the CPU should have output M2.0. A: OB100 is only used to do CPU power initialization, you may wish to monitor online can be observed, the software interface status of the progress of the lower (green) The state is still, because the power-on initialization OB100 in the program after scanning a cycle into the OB1 program cycle scan. then you
