文档介绍：通信专业外文翻译--理解S7--200网络通讯的基本概念
英文原文
Understanding the Basics of S7-munications
Selecting munication Interface for work
The S7-200 is designed to solve munications working needs by supporting not only the simplest works but also supporting works. The S7-200 also provides tools that allow you municate with other devices, such as printers and weigh scales which use their munications protocols.
The S7-200 supports many different types works. The selection of work isperformed within the Set PG/PC Interface property dialog. A work is referred to as an Interface. The different types of interfaces available to access works are:
1. PPI Multi-Master cables
2. munication cards
3. munication cards
To select munication interface for STEP 7--Micro/WIN, you perform the following steps. See Figure 7-1.
1. Double-click the icon in munications Setup window.
2. Select the interface parameter for
Figure 7-1 STEP 7--Micro/munications Interface
PPI Multi-Master Cables
The S7-200 munication through two different types of PPI Multi-Master cables. These cable types munication through either an RS-232 or a USB interface.
As shown in Figure 7-2, selecting the PPI Multi-Master cable type is simple. You perform the following steps:
1. Click the Properties button on the Set PG/PC Interface property page.
2. Click the Local Connection tab on the Properties page.
3. Select the USB or the port .
Figure 7-2 PPI Multi-Master Cable Selection
Tip
Please note that only one USB cable can be used at a time.
Tip
Examples in this manual use the RS-232/PPI Multi-Master cable. The RS-232/PPI Multi-Master cable replaces the previous PC/PPI cable. A USB/PPI Multi-Master cable is also available. Refer to Appendix E for order numbers.
Using Master and Slave Devices on a work
The S7-200 supports a master-work and can function as either a master or a slave in a work, while STEP 7--Micro/WIN is always a master.
Masters
A device that is a master on work can initiate a request to another dev