Emerson Exchange 365

Hi Alan,

I will begin by asking:
What is the customer interested in capturing?

While I wait for your response, here are some useful things to consider:
Data Logging offers two File Types: .csv and .txt
Neither of these file types has a limitation except for the available space on the harddrive that it is being written to.
For ease of organizing and analyzing the data, Emerson Service tends to save as .csv and open using Microsoft Excel. This is where we are likely to encounter the first limitation: Microsoft Excel is limited to 1,048,576 rows.

For example, let's say you connected to the transmitter with an RS485 / Modbus modem and set a Logging Interval of 1 second. The name of each value being measured, e.g. "Time, Density, Mass Flow Rate" is saved to the top row, and all recorded values are written in the rows below that. So, you could record 1,048,575 rows of values in a .csv file and open that in Excel. Dividing 1,048,575 by 60 gives us 17476.25 minutes, divided by 60 gives us 291.27 hours, divided by 24 gives us 12.1362847222 days, or ---12 days, 3 hours, 16 minutes, 24 seconds. -> This is how long you could record at a 1 second logging interval. It is longer than your customer has requested, and faster recording intervals are available via modbus. However, HART BELL 202 cannot log so quickly. Depending on the number of values that you are recording via HART, Data Logging via HART might only capture once every 15 seconds or so. This can allow you to run for longer period, and trend some variables, but is likely to miss intermittent alarms or briefly aberrant behavior.

Now, since your customer is only looking to record for 36 to 48 hours, you are well within the limitations described above. You could theoretically collect as often as 17.28 milliseconds for 48 hours, but then we would be testing the limitations of modbus, and I haven't seen a situation where this would be necessary.

When running this kind of logging, you want to be sure to have the computer on a reliable power source (plugged in), with windows sleep and hibernate power settings turned off, so that the computer does not turn itself off after a period of inactivity. ProLink will keep running as long as the connection is left alone and powered. You can enable the Data Logging Timer to stop recording at a time and date that you specify.

FYI: If you ever needed to record beyond the million line limit, you could save as .txt or open .csv in notepad, then import 1 million lines at a time into excel.

More FYI:
When considering replacements, upgrades, and new installations, you (and your customers) might be interested in Emerson's newer Micro Motion 5700 transmitters with a built-in historian.
The following info on the historian is copied from the 5700 manual:

The historian in the [5700] transmitter's working memory contains a minimum of 4 weeks of 1-second raw data and 10 years of 5-minute average data.
Each record contains data for the following process and diagnostic variables:
• Timestamp
- Format: Military time
- Time and time zone: Transmitter clock
• Mass flow rate (kg/sec)
• Volume flow rate (l/sec) or GSV flow rate
• Density (g/cm³)
• Line temperature (°C)
• External temperature (if available)
• Pressure (if available)
• If concentration measurement is enabled:
- Standard volume flow rate
- Net mass flow rate
- Net volume flow rate
- Referred density
- Concentration
• If API referral is enabled:
- CTPL or CTL
- Corrected density
- Corrected volume flow rate
• Alert status registers (hexadecimal format)
• Live zero (kg/sec)
• Tube frequency (Hz)
• Drive gain (%)
• Left pickoff (filtered) (V)
• Right pickoff (filtered (V)
• Left pickoff (raw) (V)
• Delta T
• Case temperature (°C)
• Voltage applied to the core processor (V)
• Temperature of the core processor board (°C)
• Temperature of the transmitter electronics (°C)



Best regards,

Travis

In reply to alan thomas:

Hi Alan,

Just to be clear, the Service Port (terminals 7 & 8 on 1700/2700 transmitters) is only for RS485 connections. HART connections would be made using terminals 1 & 2.

15 seconds via HART was just an estimate. I would recommend testing the Data Logging with your connection for a minute or so to get an idea of what to expect. You can select the values that you are interested in (de-select the ones you don't need) and set the logging interval to 1 second, then run for about 1 minute and stop. When you open the saved file, look at the timestamps of the samples to get an idea of your actual logging frequency. With HART, it won't be every 1 second, but as often as the connection can manage.

Is this plan to capture logging information part of troubleshooting an issue in the customer's installation?
If so, please provide some more information about the issue, and we can try to assist further.

Best regards,
Travis