Thursday, February 2, 2012

Citect SCADA and PLC





In broad applications where Citect SCADA has to apply to a lot of Siemens PLC's, a need has occurred to have a higher capability interface of Siemens Driver. SimaticNet has many limitations on the PLCs number it can relate to and also the Siemens API performance has been an issue. Citect also required a method to optimize the method the SCADA corresponds to the PLCs, because it was too simple to make setups that overwhelmed the driver of S7NT - mainly if the user tried to poll great designs of Function block instance DB's directly.

The ProSCADA Citect straight interface driver is a front-end or back-end driver, meaning that the driver contains of 2 parts:
• The back-end sets the data in a cache of memory.
• The server back-end polls the data from the configurable intervals PLC.
The front-end is an inhabitant driver of Citect which interprets the data from the cache immediately with 0 delay.

Benefits of the Citect Drivers
1. The data polling is entirely de-coupled from the time at which the users are requesting it, it means the users cannot choke up the server IO with demands, no matter how poorly the system is constructed.
2. All polling is dynamic & client triggered with a traditional Citect Driver. With this driver every data block has an individual time of poll. This lets each data block to be optimized to poll as SLOW as is suitable for that sub application. This leaves more sources presented for other data that requires to be faster.
3. The data is already exist when an user polls it and data is showed straight away with no delay.
4. The back end polls raw data blocks from the PLC. The frontend can then ask for any type of data from this one block. This effect in significant efficiencies when you have a lot of mixed types of data in close address closeness. The driver of Citect S7NT would produce a poll for every type of data whereas this driver would interpret the information in one bytes network poll block to be saved in the cache, the driver of Front end then processes a Citect Driver ask for each type of data from the same data cached.
5. The communications can be designed and debugged outside of Citect. The data can be interpreted from the same cache with a simple client of OPC before or while Citect is working.

Benefits of the Solutions of Siemens Softnet
To setup SimaticNet of Siemens on a PC and to check the communication can be very deadly. Multiple servers of IO have to be utilized to correspond to more than 20 PLC efficiently.

The driver of ProSCADA will get 5 minutes to install and operate a test with OPC. The driver runs with any standard 1GB, 100MB or 10MB card of Ethernet. More cards of Ethernet can be applied to communications to PLCs, though there are no actual performances or reliability gains. The driver runs similarly well sharing Windows workgroups, Citect, & Siemens ISO through 1 card of Ethernet. A good Ethernet control handles diverse network node isolation and link speeds.

Siemens has propaganda of marketing shocking people into buying their costly cards with graphs displaying performance of bottlenecks at the card of PC. The PLCs are the bottleneck & the total bandwidth of Ethernet utilized by the SCADA PC Ethernet card is less than 5%. This driver maximizes the statement to all the PLCs in the network by realizing a multi-threaded strategy of parallel polling. It has been confirmed that on a system with 80 000 IO and 50 PLCs.


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