Connecting Honeywell UDC via Modbus TCP/IP to Modicon quantum


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Got a project coming up that requires a honeywell udc temperature controller to be connected via modbus TCP/IP and an noe card to a modicon quantum plc.

This will be my first time using anything modicon and am getting very lost reading various manuals and application notes on how this should be done.

first question is this even possible with the proposed hardware?
> Got a project coming up that requires a honeywell udc temperature controller to
> be connected via modbus TCP/IP and an noe card to a modicon quantum plc.

The UDC talks Modbus over ethernet. I can't help you with the Modicon side.

In general, for Modbus comm with a Honeywell UDC here's some tips:

Summary: You get a UDC that can talk Modbus over ethernet, you give it an appropriate IP address, you enable Modbus and ethernet communications on the UDC, you plug it into an ethernet switch and then from the master read the PV to make sure everything is working.

The devil is in the details:

1) You didn't mention which Honeywell UDC and the series has been on the market since the late 1980's. Only the latest series, the 2500, 3200 and 3500 UDC's talk Modbus over ethernet; the earlier models do not.

2) The protocol the UDC's talk is not the licensed Modbus Plus. Make sure the Modicon is not talking Modbus Plus to the UDC, because the UDC doesn't talk Modbus Plus.

3) The Modbus ethernet card is optional on the UDC. The card can be added to UDC's that are not already so equipped.

4) Early (circa 2006) UDC firmware revisions had serious known bugs. I don't have a UDC around to check the paper label on the ethernet card to get a current firmware revision number, but it will pay dividends to get a recent version ethernet card for UDC. A word to the wise.

5) IMPORTANT: Pay no attention at all to the Modbus documentation (chapter 9, Modbus RTU Function Codes) in the regular Product Manual that comes with the UDC. The regular Product Manual refers only to operations and registers associated with decimal function codes 20 and 21 (14,15 hex), used to read or write configuration data to or from the UDC (which you are very unlikely to use). The Product Manual warns about this on the first page of the chapter, but it's easy to overlook.

The commonly used function codes 03/04 06/16 are well documented in a downloadable Modbus manual. The downloadable manual covers models than the UDC's, but it is complete in its documentation of the UDC's.

The current document is Modbus RTU Serial Communications User Manual 51-52-25-66, Feb 2009.

downloadable from this search results page:
or the corresponding tiny URL:

Even though the title is Modbus RTU, the contents apply to the UDC ethernet communications.

(Right clicking and doing "save target as" avoids whatever Honeywell's "download list" exercise might be)

Be warned that there are numerous revisions of this document. At one time, Honeywell conscientiously noted the revision of the manual with an alpha character at the end of the document number, but the most recent version does not have a suffixed alpha character. The last version with an alpha character was Q, dated April 2007. Earlier version are quite antiquated. I strongly recommend avoiding earlier versions.

6) The UDC's IP address can not be configured from the front panel. Go figure. The IP address can only be configured with PIE software that runs on a Windows box or an HP pocket PC.

Frequently, a distributor has the software and the IR dongle and can change the IP address for you. The default IP address is

7) The UDC's Modbus communications is enabled in a group of COM settings accessible from the keypad. Enable ethernet and Modbus.

8) A careful reading of the register tables will reveal that the UDC has floating point in one table and integer format in another table. Table A.3, Loop Value Integer Register Map, has details about an integer's decimal point or scaling is provided.

Table A.5 Loop Value Register Map has all the floating point registers.

The UDC has choices for four floating point formats. The two most common are FP B and FPLB. If you're reading a floating point register and the numbers are really whacky, change to other of the common formats (using keypad on the UDC) and chances are 99 out of 100, the FP number will then appear correctly.

9) The quickest check is to read the process variable (PV), the value that appears in the UDC's upper display.

Use function code 03 to read 40065 (0040h) for a floating point value, or use 03 to read 40001 for a signed 16 bit integer value, scaled by a factor of 10.

Make sure you have an input of some sort connected when you read a PV or you get a fault code. If you're working on the bench and don't have a field instrument to connect to, configure input 1 for a J, K or T type thermocouple. Short input 1 terminals with a paper clip and the PV will display the ambient temperature, good enough for government work.

thank you for the reply and information. the udc to be used is a 3200 with the ethernet option card fitted.

I will go have a read of the manuals suggested and will more than likely be back with a few questions.
If that honeywell UDC supports modbus TCP/IP and gives the data through words then NOE can read data from that device by configuring IO Scanning in NOE module