How can a complete set of PLC-driven vacuum pumps be operated via DCS?
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Our facility currently has a set of vacuum units controlled by PLCs. We now want to use a DCS to monitor these units and adjust the vacuum level. The PLCs are Siemens S7-200 type, while the DCS is Honeywell C300 type. What hardware or wiring is needed to achieve this control? Software aspects are not a concern; the manufacturer will handle that! I need an expert to help me. . I am extremely grateful
That Siemens S7-200 PLC supports the Modbus protocol
The PLC is a Siemens S7-200, the DCS is a Honeywell C300, with communication functionality
Either DP or MODUBS – these are the two most commonly used nowadays.
There are many ways to do this, which can be simple or complex. Often, it depends on the on-site conditions. 1. It depends on the distance. It’s too far; some communications cannot be established. 2. Can a communication card be added to the PLC model? 3. If that doesn’t work, a direct wired connection can be used, without the need for communication.
For communication, only monitoring is performed; if control is required, many changes are needed – new wiring must be added to the DCS, and the configuration program is also required
Do you have the source code and drawings for the manufacturer’s complete sets of equipment? With these two in place, the control systems on both sides should communicate with each other; configuration is required on both sides as well as some programming. For the S7 200, it depends on which CPU model is used; check the manual to find out what the supported range of internal digital signals is. If you need to use many variables for communication, you need to ensure that there is enough address space available. If it’s hardwired, I guess there may not be enough space in the cabinet for installing additional IO modules; using spare IO points might not be sufficient. To cut costs, manufacturers usually design their products in a compact manner, without considering any possibility of expansion.
The flow diagram of the original vacuum system is needed; changes can be made based on that flow diagram for control design purposes……
The DCS is used to monitor and adjust the vacuum level of the unit; to enable such monitoring and adjustment, signals must be sent to the DCS. Pressure transmitters must therefore be installed on-site. I’m not sure how you guys adjust the vacuum level – how exactly is it done? Control valve?