Frequently, customers complain that Siemens' panel and plc communication are slow, but in many cases it is caused by improper settings. Some settings are listed below, which will affect the communication speed between the panel and the PLC. Shenzhen Jinziming Electronic Technology Co.,LTD , https://www.powerchargerusb.com
1. Variable refresh cycle In the normal communication mode, the minimum refresh cycle that the panel can support is 100ms.
Is the shorter the setting, the faster the communication? This is basically the case when the variables are few. But if there are many variables, it is not. Because a large number of communication tasks are executed for much longer than the refresh cycle, communication jams will result. The performance is that the communication speed will decrease. Therefore, according to the actual needs of the project, the variable refresh cycle should be long and short.
For some special applications, such as direct keys. The panel can then be configured as a DP slave. This ensures a fast transfer of some critical data.
2. Variable Acquisition Mode Variables have three acquisition modes, loop continuous, cyclic use and according to commands.
By default, we should set it to the way it is recycled. This means that only when a variable is used in the current picture, the variable will be refreshed to generate a communication load. If the error is set to loop continuous, the panel will continuously refresh the variable in the background regardless of whether the variable is used in the current screen, thereby generating unnecessary communication load and reducing the overall communication speed of the panel.
A common application for setting the loop continuous mode is that the variable has a value change event configured.
3, the communication baud rate is of course the faster the better, the premise is that the line quality is good, less interference or grounding shielding and other measures are appropriate. When the communication conditions are poor, the high baud rate leads to a higher probability of communication failure, which in turn reduces the speed of successful communication. If the baud rate is reduced at this time, the probability of communication packet errors is reduced, thereby improving communication speed.
4. Number of I/O fields in a single screen Each panel will give the maximum number of objects allowed in a single screen in the performance parameters, such as up to several fields, up to several variables, and up to several complex objects. These are the limit parameters. The actual application of the project does not recommend that these parameters reach the limit, unless the project is relatively simple and there are not many communication variables. So, if possible, split the picture of the multi-I/O field into sub-pictures.