nigel s
Member
Hello chaps; I wonder if anybody could point me in the right direction?
I need to specify (& eventually program/commission) a control system for a test chamber which will be used to assess the performance of supermarket style refrigerated display units in accordance with BS EN 441. The control side of the job is simple & comprises just 3 PID loops for temperature, humidity & circulating air velocity. But we also need to monitor & log approximately 30 analog inputs from sensors on the appliance under test over a 24 hour period (I'm not sure at this stage at what kind of time intervals until I get access to the BS document but could be say 5 minutes) & then - after some calculations relating overall energy input to actual refrigerating capacity generate a summary in Excel format.
I think the question would be - is this a basic PLC plus SCADA application or would the number of analog inputs - which are only being logged - require a more complex PLC than could be justified?
Is there maybe a way of using a very minimal PLC for the control of conditions in the chamber, & some other means of data acquisition & processing for the analog inputs?
I envisage that we'll be using a touch screen as an interface to the system. I know some of the HMI's available can have quite a lot of inbuilt intelligence but am uncertain as to whether they could handle the logging & calculation aspect.
Has anybody done anything similar?
I need to specify (& eventually program/commission) a control system for a test chamber which will be used to assess the performance of supermarket style refrigerated display units in accordance with BS EN 441. The control side of the job is simple & comprises just 3 PID loops for temperature, humidity & circulating air velocity. But we also need to monitor & log approximately 30 analog inputs from sensors on the appliance under test over a 24 hour period (I'm not sure at this stage at what kind of time intervals until I get access to the BS document but could be say 5 minutes) & then - after some calculations relating overall energy input to actual refrigerating capacity generate a summary in Excel format.
I think the question would be - is this a basic PLC plus SCADA application or would the number of analog inputs - which are only being logged - require a more complex PLC than could be justified?
Is there maybe a way of using a very minimal PLC for the control of conditions in the chamber, & some other means of data acquisition & processing for the analog inputs?
I envisage that we'll be using a touch screen as an interface to the system. I know some of the HMI's available can have quite a lot of inbuilt intelligence but am uncertain as to whether they could handle the logging & calculation aspect.
Has anybody done anything similar?