Modbus Micro Motion Problem


Thread Starter


I have an Scada Pack Light from Control Micro Systems, and a Micro Motion Flow Meter model CMF300M425NABAEZZZ connected to a Emerson Transmitter model 2700R11ABAEZZZ, and this transmiter have some floating point variables in the 2XXXX and i cant readed, i think is because my RTU(Scada PAck) have the 96 Modbus implementation. Could somebody helpme?
R: I found this browsing, maybe it will shed some light on your problem, I copied it verbatim.


Re: Accessing data in Wonderware using Modbus
Feb 2, 2004 10:59 pm, by Joe Malter
If you are using the standard Wonderware Modicon driver then address the volumetric flow rate in floating point by entering F30253 as the item name. (use F30247 for mass flow) The I/O server interperets the F as a floating point and will read the register pair 30253/30254 as an IEEE 32-bit float. I think the I/O Server swaps the high/low word. If not you may have a problem.

The Micromotion Modbus manual indicates floats as 20000 registers. Use the same address but 30000 instead of 20000. This works for any of the floats in the manual.

Let me know if you are using another I/O Server. Some perform the word swap, but how to do it is not always obvious.

Good Luck,

Joe Malter
Pipeline Systems Inc.
[email protected]

Lynn at Alist

I think you mean 4x20000 range, correct? MicroMotion uses K-ranges (thousands) to define the type & size of the data. So you mean registers like 20001, etc, but still using the 4x functions. As long as Control Micro Systems (CMS) supports addresses from 0 to 65K and is not limited
to 0 to 9999 you should be Ok. I don't know about CMS's support for 32-bit floating point responses.

The Modbus 2X point type is long obsolete and related to some old drum sequencers (so I have been told). I am sure MicroMotion is *NOT* creating a new acccess type. I have used MicroMotion many time in truck loading systems.

best regards
- LynnL,