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I have a control system where the PLCs stamp the time to each value they receive. The SCADA that I use is the iFIX, and the problem is that I don't
know if there is someway to get at the same time the value and the time stamp of a signal from PLC with iFIX? If it is possible, how can I do it?

Thanks in advance.

Juan Jose Franco
ufisa soluziona
Tlfo.: +34 91 384 71 00
Fax: +34 91 384 71 99
[email protected]

Dean Kindrai

There are several ways to accomplish this; thay depend on how accurate you want the time stamp to be, and what type of PLC you are using...

If your time stamp needs to be very accurate, I suggest you contact Monaghan Engineering in Houston, TX. Their number used to be (713) 859-5205, but they may have had an area code change. They make a Sequence Of Events recorder module for several different PLC models accurate to +/- 1mS, and some are capable of using a satellite signal to coordinate time.

If you just need to have the times match to +/- a second or so, you could add a script to your HMI program to automatically set the "real time" clock on your PLC at a specific time each day on your HMI PC. (For example, at midnight each night run a script that sets the PLC clock to midnight.) I've done a lot of this with Modicon PLC's on SCADA systems and I find it good to about a second a day. You may find that you need to run this routine more than once a day - PLC clocks are notoriously bad at remaining accurate.

-Dean Kindrai
Neff Engineering of WI

Darold Woodward

Collection of information with highly accurate time-stamps is a very common issue in utility projects. Timestamp accuracy and resolution are typically in the millisecond range.

The Monaghan modules use a special driver for (I think) Intellution HMI software and a custom loadable in the Modicon PLC. The special driver actually is able to collect both the new value and the time stamp and give you a way to reference
them. It may also push the data into the HMI's historical log. The problem here is that HMI software does not generally have the capability to understand "event objects" (or any other data object) that includes more than one attribute. Especially when you are collecting that data across a non-object oriented (like Modbus) interface.

You may have some luck using a protocol like DNP that includes event objects. You still need to decide on how to collect them and store them in a historical log in the HMI. With the Standard Automation DNP driver, you can create a log
of event data from the driver, but it is not integrated into the HMI historical log.

There are also some other SER (sequence-of-events recroder) manufacturers that offer a Modbus interface as well as their own protocol. Again, the HMIs are not equipped to deal with the data so you must have add-ons to the HMI or run
software from the SER module vendor to collect and log the data.

Darold Woodward PE
SEL Inc.
[email protected]
[email protected] wrote:

> Collection of information with highly accurate time-stamps is a very common
> issue in utility projects. Timestamp accuracy and resolution are typically
> in the millisecond range.

Just an observation, chips that implement the semi synchronous CAN protocol do offer some support for a synchronised counter. Does anybody make use of this in automation?
As has been mentioned, the conventional HMIs have a problem accepting data with a timestamp. IN the communications environment, the data can arrive at
the computer with some delays adding to the requirements for both displaying the data currently and recording the sequence of events.

Our Vsystem can accept accurate (nanosecond) timestamps out of time sequence and display and store them with the data.

Peter Clout

Peter Clout
Vista Control Systems, Inc.
176 Central Park Square
Los Alamos, NM 87544-4031
(505) 662-2484
FAX (505) 662-3956
[email protected]
This isn't much of a solution, but eMations Wizcon (www.emation.com) supports remotely generated timestamps to millisecond accuracy.

I've created elaborate device drivers that pass time stamped data directly to the Wizcon database. If data arrives out of order, Wizcon will open the database and insert the data in the correct temporal order.

A VERY useful feature.

Mark Hill
[email protected]
For a 80MW hydro electrical power plant I've done a solution for presenting plc-time stamped events using Fix32. The problem with FIX32 was that the alarm time-field of the Fix tag was not accessible by the any script command(This should be fixed in iFix, but I'm not using it). [In FactoryLink the Alarm time is overridable] The tag Description field is though, allowing a script to insert the plc time in the text. This does give you some limitations on the description text length, originally 48(?) takeaway "hh:mm:ss:ms " = 13 chars, leaving 35 for your event desription - not too much. Date info is taken from the pc, but time is accurate to 10 milliSeconds in my system. The queued events are polled from the plc using a telegram containg plc id, signal id, and time values. The VIEW macro script is looped forever and used for combining the information needed to access the correct tag in Fix. Off course tag namnes need to have a numerical array naming convention instead of logical names. The sript has looped successfully for 2 years now and still goes on. The script also writes to a text file. This text file is viewed using the shareware program TextPad, set to Auto ReLoad, scrolling the events as they come in. Fix32 handles the printing of the same events using alarm areas that are only printed, not viewed. Some workarounds, some double definitions - but it works. Feel free to e-mail me. [email protected]