Project: Baton Rouge Wastewater Pump Station SCADA System (February 21,2006)


February 21, 2006

Monitoring of bandwidth usage during the past week indicates our current polling scheme is not very data efficient. We need to stay within 2 megabytes per month data usage per site or data transmission charges will soar vs. the allocated budget. Considering the 27 words of data to be transferred, one might be led to believe updates every few minutes would be possible. The reality is that to send and receive a Modbus message, there is considerable overhead. To reduce the impact of the overhead, bits are preferably packed into words, and words are kept sequential within the RTU memory map so that one Modbus function call can read a series of registers in one request. Lacking a bit packing function, we have used a sequence of if/then statements to pack bits into words. The original RTU programs were not written sequentially (and could not be written sequentially due to controller addressing requirements). Moving values around inside the controller to force data into a sequential block will allow the OPC server to read all values in one read.

The primary consultant announced last week that they intended to have a PLC and HMI recommended and selected within the next two weeks. Seeing will be believing—past history indicates this projection is probably overly optimistic.

No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Make Big Data and Industrial Internet of Things work for you, 2017 Engineers' Choice Finalists, Avoid control design pitfalls, Managing IIoT processes
Engineering Leaders Under 40; System integration improving packaging operation; Process sensing; PID velocity; Cybersecurity and functional safety
Mobile HMI; PID tuning tips; Mechatronics; Intelligent project management; Cybersecurity in Russia; Engineering education; Road to IANA
This article collection contains several articles on the Industrial Internet of Things (IIoT) and how it is transforming manufacturing.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

SCADA at the junction, Managing risk through maintenance, Moving at the speed of data
Flexible offshore fire protection; Big Data's impact on operations; Bridging the skills gap; Identifying security risks
The digital oilfield: Utilizing Big Data can yield big savings; Virtualization a real solution; Tracking SIS performance
click me