PLCs commissioning times


Thread Starter

Martin Webb

We have a relatively simple control system that consists of 2 modicon Quantum PLCs, approx 1000 I/o, that are a mixture of simple digital I/O and 4 to 20mA analogues. There are four PIDs. There is a SCADA server running Factory link7, and 3 workstations. Please can the list members supply advice on factors affecting time taken to set to work and commissioning the above system, and if possible supply workable setting to work and commissioning times metrics/ estimating rules of thumb that can be applied to such a system. Thanking you in anticipation Martin Webb

Bob Peterson

Thats a tough one. 1. I find that actually checking the PLC code, SCADA stuff, and sequence of operation goes pretty quick and is fairly easy to estimate the time requirements for. I have control over the quality of this work and can assure it is done right the first time. 2. I cannot control the quality of the field work that is done. It is impossible to even estimate what it is going to take to check, debug and fix the field work. 3. And many times the mechanical system(s0 and seqeunce of operation have been poorly thought out by the designers requiring substantial field changes to make it work. These also cannot be estimated. 4. Some times we are called upon to only write software and thus end up having to checkout enclosures built by others. My experience with this runs from no big deal to big pain. Usually if the panels are built by another integrator's panel shop they have been ok. The worst problems seem to come from OEMs that build their own panels. Typically I find that that item 2, 3, and 4 above take far more time then item 1, and since they are unknowable it is just about useless to try to estimate field startup hours. Bob Peterson
Bob, Thanks for the info. You dont mention the field you are operating in. The sentiments in your points 2,3 and 4 have been voiced to myself by others. For our particular situation, the overall hardware/software design has been done by one company. The software implementation (both PLC and SCADA) is being done under subcontract by a sytem integrator. The instrument and field wiring is in the process of being installed and checked out by our ME&I installers, the PLC cubicle and SCADA hardware is being manufacturered by the same system integrator that is producing the software. The ME&I installer will verify the hardware installation. The system integrator will verify both the PLC/SCADA hardware and the software, as far as practical. The risk areas are therefore in the integration and setting to work of the complete system. Would any of this information alter the points you made in your email. Thanks Martin