Key word: Haiwell domestic PLC, Remote IO,Computer monitoring, Mobus communication protocol
Oilfield water injection monitoring project is not complicated in itself, mainly to monitor operation of the oilfield water injection system equipment and process parameters, including pressure, temperature, flow, voltage, current, set equipment safety alarm for Protection according to the parameters.
Project features: Many analog points (this example project 88 points), monitoring points are scattered
● System stability
● A powerful communication expansion ability
● High real-time function
● Simple implementation, short construction period
● The configuration software will display monitoring parameters. 88 points to reach the upper or lower limit need alarm, 27 points to reach the lower limit or upper limit, the need for emergency stoping
● Upper computers monitor at the same time, each independent, one computer failure will not affect the whole system monitoring
2. Control system selection
There are many control systems that can be used, there are many successful cases, in general there are: PLC system, data acquisition system, single chip microcomputer system.
PLC system: Other small PLCs can not realize this kind of project, because the analog points are many and it requires a strong communication expansion, so usually it requires the medium-sized PLC, such as S7-300. The disadvantage is that its cost is too high.
Data acquisition system: It has a very strong expansion, suitable for decentralized remote installation, such as the Adam module. The disadvantage is the lack of real-time function, weak in control.
SCM system: for system development, the shortcomings is lack of flexibility, weak in expansion
Reason for selecting Haiwell
● Haiwell PLC with the CE certification system is stable and reliable, and cost-effective to save investment costs.
● Programming is simple and convenient. The built-in simulator greatly reduces the on-site debugging time.
● The analog module can be local parallel expansion, remote installation can also be distributed as remote IO, not limited by the expansion of AI / AO points and can control big system with many I/O points.
● Haiwell PLC support five communication ports, strong real-time function,, the size of the program does not affect the communication speed,.All communications are completed by a single instruction .It can run with electricity,no need to consider the communication port conflict, send and receive control signal, handle communication interrupt ect, do alarm for any node communication failure
3. System network diagram
PLC configuration: (8 DI, 32 DO, 88 Analog input points, 3 communication ports)
● The host: HW-S16S2R 1 set
● AI module: HW-S08AI 11 units
● DO module: HW-H36DOR 1 set
● Expansion of communication modules: HW-H01RS 1set
The network diagram is as follows:
4. Part of the program description
● Remote IO acquisition and remote station failure alarm: using Modbus reading instruction MODR will read 8 channel values of every remote IO module and fault code to the PLC host, fault code is reported 0 module failure, failure to communicate with the module continuous 1 second is reported with the module communication failure.
PLC application in the oil field water injection monitoring system
● High alarm, higher alarm, low alarm, lower alarm: Haiwell PLC provide a high limit alarm HAL and low alarm LAL instruction. HAL and LAL instructions differ from the general compare instructions is that they have dead zone function to avoid frequent alarms due to numerical fluctuations.
PLC application in the oil field water monitoring system
● Upper computer software: You can use the SCADA configuration software. The SCADA can be installed in the computer 1 and the computer 2 at the same time.