Hi,

Has anyone connected the new DT85 with a PLC through MODBUS? I am wondering if I could connect all my sensors to DT85 and send all CV data to a PLC using MODBUS TCP/IP or RS-232.

Will the MODBUS communication be real-time (every second) or PLC will only receive data based on my logging schedule?

Cheers,
Ken

Good afternoon Ken,

This is exactly what the Modbus Slave set up in the DT85 is for. The section in the DT80 series manual does a good job of explaining how to configure the dataTaker.

it can do either Modbus TCP/IP or Modbus RS232. You read the data into a channel variable and the channel variables are mapped to the Modbus registers. The dataTaker can be set to run at what ever sample speed you wish all you need to do is read the registers as required.

Cheers,
Roger

Hi Roger,

Thank you very much for your advise. Just another question, it the setting for registers reading and logging schedule the same interval? Which mean could I logging data at an interval of 5 mins but send the CV data to PLC through MODBUS at an interval of 1 sec?

Look forward to receive you reply. This new DT85 is really a fantastic logger!

Hi Ken,

The register, that is CV's, are updates at the dataTaker scan rate. You can read faster but you will only get the same value until the DT80 updates.

Yep they are a great little unit and they just keep getting better.

Cheers
Roger

Hi Roger,

I have posted this article some time back and finally I got the DT85. I have been using DT500 with Delogger4, and I have no problem setting the decimal point for the datalogger.

However, I can't seems to find the setting for decimal point in Delogger5. I tried to use De-transfer to set "/h" & "81CV (FF1)" as advised in the manual, but the reading in my downloaded CSV sheet still display in 8 decimal point. For your info, I am using Deload to download the records. What should I do to obtain data with 1 decimal point?

Another thing is on the MODBUS communication. I have successfully setup my PLC with DT85 via MOBUS TCP/IP and data is coming in from the DT85 to PLC. However, even if I set the schedule rate to 1 sec, the reading in my PLC will only update in every 10 secs. Is there anything that has affected the updating rate?

Look forward to your reply. Thank you very much!

Good afternoon Ken,

1. Fixed format mode and DeLogger
   DeLogger uses fixed format mode, it must have the data returning to it in the same format every time so it knows exactly where and how to parse the data and so it won't allow you to change anything that would affect the format of the data returning from the logger.

   You can change the way the data is presented in DeLogger. you can set up the number of decimal places displayed

2. Fixed format mode and DeLoad
   DeLoad like DeLogger uses fixed format mode when unloading the data and the reasons are the same. DeLoad reads the data in fixed format mode and then translates it to the format you require.

3. MODBUS
   What is the scan time on the PLC?

Cheers,
Roger

Good Afternoon Roger,

1. Thank you for your reply. I understand on the fixed format mode. Does it mean that there is not way to set the decimal place if I used Deload to download the data? And in Delogger, how should I set the decimal place? I could not find the internal properties function for CV in Delogger5.

2. Clear

3. The scan time for PLC is set to 1 sec as well.

Best Regards,
Ken

Good afternoon Ken,

1. Down loaded data format.
   With fixed format mode you and only change what is being displayed on the screen. You can't change the data that is being down loaded, so sorry but can't you can't change the number of decimal places in your data when using fixed format mode.

2. I'll have to set something up here to test the update rate but I do seem to remember it working correctly. In the mean time have you tried looking at the data with MODBUS poll? Checking if there is an update time limitation some where is the system?

Cheers,
Roger

Hi Roger,

1. Just curious why the format of the data could be configured using Delogger4 but not Delogger5? Anyway, I will try to talk to my customer to accept data with 8 decimal places.

2. I am able to have 1 sec update when using MODBUS POLL. So it looks like my PLC is delaying the data refresh. I will dig into the configuration and see if I could find any scan time setting then.

Anyway, thanks a lot for your help! The DT85 has a lot more interesting features to play compared to DT500.

Best Regards,
Ken