Applies To:
  • CitectSCADA 5.xx, 6.xx
  • CitectHMI 5.xx, 6.xx
Summary:
What is the optimal Citect communication setup for the S7 driver?

Do I configure Citect to use 1 port per I/O Device, or do I configure Citect to use 1 port for multiple I/O Devices?

 

Solution:
Changes have been made to the S7 driver to reduce response time from the PLC and hence increase performance for large projects using multiple S7 PLCs.

1. If your Citect I/O Server is communicating to multiple Siemens S7 PLCs, then it is recommended that you configure your communication setup to use 1 port per I/O Device. This means that you will need a unique VFD Name and Connection Name for each of your port/I/O Device pair.

2. With multiple S7 PLCs on the network, the S7 driver will take longer to initialise and bring all of the I/O Devices online. Depending on the speed of your LAN network and the type of PLCs used (eg. S7-300 or S7-400), you can also adjust the

parameter [S7NT]ConnTimeout. This parameter is used to control how long to wait to bring an I/O Device online during initialisation.

3. For "small" projects, you can also configure your Citect I/O Server to use 1 port per I/O Device for optimal performance. You can also use multiple I/O Devices per port if you are using the older Siemens Softnet V3. The Siemens Softnet V6 only allows a maximum of 10 connections or "channels" for external applications such as Citect. It can however support up to 64 Devices/PLC's to be shared among these 10 connections. If you require more than 64 PLC's on a single I/O Server, you can alternatively use the PSDIRECT driver

Note:
With PSDIRECT it is required that ALL IO devices are connected through one port.  PSDIRECT operates in a different way to many other drivers in this regard.

 
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