DeltaV Modbus Timestamp

Hi there!

Is there a way to make use of timestamps with deltaV Modbus - either EIOC or VIM2 modules?

We are designing a system to interface DeltaV VIM2 card to a gateway device (GE Multilin G100) via Modbus TCP and we would like to include timestamped data as part of the Modbus protocol.

I know that it is not standard to include timestamps with Modbus but I have come across some example systems that use spare 32 bit registers, for example the Emerson Smart Wireless 1420 Gateway which supports DeltaV).

The reason for this is that the gateway implements IEC 60870-5-101 protocol which uses timestamping for digital signals. 

For example, if we send a digital feedback signal (e.g. breaker state open) from DeltaV via modbus, we want to include the timestamp data too.

Any suggestions or ideas would be appreciated!

Thanks

4 Replies

  • One could use Unix Time / Epoch time and only takes a couple of registers. This would be a 32 bit register that in a unix system is the number of seconds since 1970. A lot of devices support this. DeltaV has the same functionality except that theirs is seconds since 1972, so you have to adjust by 2 years (easy add or subtract correct number of seconds for 2 years) depending on what the remote device might support. Within DeltaV, you can use the TIME_TO_STR and STR_TO_TIME functions to convert to human readable formats. Keep in mind this would be subject to the 2038 problem which is when a 32 bit integer would roll over.

    However, almost any solution is going to be what does the foreign device support for this. If it doesn't have any timestamp capabilities at all, you might be limited in what you can do.
  • In reply to Matt Forbis:

    Thanks for the reply.

    Can you provide more detail on the DeltaV modbus implementation of the timestamping? Where would this be configured?
  • In reply to Matt Forbis:

    Hi Matt

    We need the time to include milliseconds. Is there another time function that caters for this?
  • In reply to Sarah Hart:

    I'm not aware of any time functions in a controller that let you parse milliseconds. If you are sending it over the modbus link, you might be able to capture and store what is sent, but I don't believe there would be any good way to log an event or process the time stamp. Keep in mind, in most cases, modules in DeltaV are usually running much slower like once a second (yes, PK's support to 25 msec and M/S support 100 msec, but most people don't run there.