X Series Application Note 34 Using Acromag 967 Modbus/TCP module as Remote I-O with the X-Series Recorder

Transcription

1 X Series Application Note 34 Using Acromag 967 Modbus/TCP module as Remote I-O with the X-Series Recorder 43-TV-07-34, July 2012 Summary: Many applications require the recording of signals from devices that are not in close proximity to the recorder. In cases like these, one solution is to use communications and remote I/O devices like the Acromag 967 to get these signals to the recorder. These modules serve as an interface for high level analog input signals to an Ethernet network as a Modbus/TCP slave; making them ideal for use as remote I/O to a Honeywell X-Series paperless recorder acting as a Modbus/TCP master over a standard Ethernet network connection. Figure 1 - X-Series Recorder & Acromag 967 Modbus-TCP module as remote I-O Getting Started: The Acromag 967 provides data in either floating point or signed integer formats. Some things to keep in mind when setting up the recorder and Acromag 967 are that signed integer values range 1 to 20,000 counts across the 4-20mA input span in the Acromag device, so scaling to user friendly engineering units has to be done on the recorder. Floating point values can be scaled to engineering units in the Acromag and read directly as scaled values. If the scaling in the Acromag is correct, no scaling is needed in the recorder's pen math statement. The Acromag setup is done via a web browser, so no additional software is needed to set up the device. The X-Series recorder needs to be set up as a Modbus Master, so Credits (10 Credits) are required to enable this function; in addition to this, Full Function Math (4 Credits) or Math Scripting (6 Credits), may be required to do the necessary input scaling of the signal. If the values are being recorded to Virtual or Extra Pens additional credits (1 credit enables 2 extra/virtual pens) are required for these pens. If there are unused analog inputs, the pens associated with these unused inputs can be used for recording the Modbus data rather than using Extra or Virtual pens.

2 Using Acromag Remote I/O with X-Series Paperless Recorders Solution Note 2 X-Series Recorder Set-up: The X-Series recorder is set up using the Ethernet port as a Modbus master to communicate with the Acromag module acting as a Modbus slave; getting data from the Acromag module. The data from the Acromag module is assigned to individual pens in the recorder as a communication value using a math expression value; SCV[x,y,z], where x, y, z represents the values for the data coming from the Modbus slave device. The screen shots shown below are provided as an aid for setting up the recorder to communicate with the Acromag remote I/O device. Some of the first steps required are to make sure the proper functions are enabled and to set up the basic communications parameters for the recorder and Acromag device. Since the values are being obtained over communications, the recorder network settings needs to be set to match the TCP/IP network settings of the Acromag. 1) Confirm that the recorder is on the same subnet (xxx.xxx.xxx.yyy) as the Acromag. The Ethernet port setup in the Recorder s Comms>TCP/IP Settings (the first three sets of numbers) need to match, the last set of numbers need to be different; they need to be between 001 and ) Enable credits for Modbus master, full or scripting math, and extra pens for each Modbus value that will be polled and used. These are set in the recorder s General> Factory> Credits>Options set up screen as shown below.

3 Using Acromag Remote I/O with X-Series Paperless Recorders Solution Note 3 (16 pens use 8 credits; 8 pens use 4 credits) 3) Since the recorder will be the Modbus Communications Master, the Modbus Master function which was enabled in the Credits function can now be set up as shown below: First, open and configure one of the available Slave devices (Slave 1). Give the Slave x an appropriate Friendly Name (Acromag 967 for example). Give the device a Modbus ID (needs to be unique and between 1 and 255), this would be the same ID used in the Acromag device. Set the Network name to match the Acromag IP address. Set the Modbus protocol to be used; this must match Acromag s Floating Point byte order choice Bw, Bx, By, Bz as shown below as a mismatch gives unusable results.

4 Using Acromag Remote I/O with X-Series Paperless Recorders Solution Note 4 matches Acromag matches Acromag The next step is to set the individual Transaction to read the Modbus values from the Acromag device by selecting a Transaction and enabling it. There are four X-Series Recorder transaction Command/Data types available in the recorder. It is recommended to use the Input register/floating point format illustrated below but the others work as well but may require additional set up information. 1) IEEE Floating point format, Input Registers 2) IEEE Floating point format, Holding Registers 3) Integer format, Input registers 4) Integer format, Holding registers Note: Selecting integer format requires the X-Series recorder to do the scaling of the 0-20,000 count data value provided by the Acromag as part of the Pen Math Expression. Floating Point Format, Read Input Register code 04 Open a Transaction and Enable it. (Unassigned transactions show up as a red X, Green check mark enables the transaction) o Direction - In selects a read operation (reads data into the recorder) o Command - selects Input Registers(4) Modbus function code 04 o Data Type - IEEE float selects the floating point format o Decimal Starting Address is the indexed decimal starting address for first of 8 analog values o Number of Items this selects the eight consecutive registers to be read from the Arcomag device in a single transaction First value uses math statement SCV[1,1,1], Second value uses math statement SCV[1,1,2], Third value uses math statement SCV[1,1,3], etc. It is recommended to get all 8 consecutive register values in a single read, as this improves the efficiency of the acquisition process. o Use Acromag s Input Configuration web page to configure scaling for the data value.

5 Using Acromag Remote I/O with X-Series Paperless Recorders Solution Note 5 Integer Format, Read Input Register function code 04 Open a Transaction and Enable it. (Unassigned Transactions show up as a red X, Green check mark enables the transaction) o Direction - In selects a read operation (reads data into the recorder) o Command - selects Input Registers(4) Modbus function code 04 o Data Type signed 16-bit integer selects the integer format o Decimal Starting Address - 18 is the indexed decimal starting address for first of 8 analog values o Number of Items this selects the eight consecutive registers to be read from the Arcomag device in a single transaction First value uses math statement SCV[1,1,1], Second value uses math statement SCV[1,1,2], Third value uses math statement SCV[1,1,3], etc. o Scaling the Integer value: To do this, select the Pen being used to display and recorder the communications value (SCV[x,y,z]) and divide by the scaling factor to provide the scaled reading. (i.e. 0-20,000 count is scaled to gpm (divide SCV value by 40)) as shown below.

6 Using Acromag Remote I/O with X-Series Paperless Recorders Solution Note 6 Acromag Setup: All the configuration parameters done in the Acromag s web browser can be done via Modbus, but this solution note only addresses the critical parameter for getting the data over the communications link. The X-Series recorder uses Acromag s published Modbus decimal register values as part of the set up for getting these data values over communications. Some things to note with the Acromag's are: The Acromag s sample time is 8mS, so the Acromag data over communications tends to be noisier than the same signal wired directly into the recorder. A solution to this is to let the Acromag average multiple samples to smooth out the signal (20 is a good starting point for the average). The 200 ohm, 4-20mA analog input resistance will not unduly load a loop powered circuit, but it will inhibit HART communications (HART requires 230 ohms, minimum). Acromags i2o remote messaging function writes values only to other Acromag products. Hence, i2o is not applicable for use with the X-Series recorder. Getting Started: Power up the Acromag unit (24Vdc) and plug in an Ethernet cable, straight CAT 5 cable to PC works OK (crossover not needed). Assign the Acromag a working static IP address - The Acromag default IP address is You need to have the PC s Ethernet port onto the same subnet: x - Launch a web browser (Internet Explorer) and type in the Acromag s IP address ( ) to access the configuration Log-in default user: User (capital U) default password: password00 (lower case,.... zero, zero) Browse to the Network Configuration web page Enter a working IP address ( in this example) and click submit button

7 Using Acromag Remote I/O with X-Series Paperless Recorders Solution Note 7 Change the PC s IP address to be on the working subnet ( xx) making sure not to use the same IP address that was assigned to the Acromag. Log back into the Acromag using the new working IP address ( ) via the browser with the same user (User) and password (password00) Navigate to the Input Configuration web page and select a channel (each channel is independently configured) as shown below. Input Type: Select the input type (typically 4-20mA) o If reading floating point, the Acromag s scaling can be used. The values are IEEE 754 formatted, which works well with the Honeywell FPLB or FP B byte order formats. Enter the zero and span range scale values. o If reading integer formatted values, the Acromag s scaling has no effect. The Acromag s integer values are 0-20,000 ranged over 4-20mA range. So, for reading integer format, skip the ranging. Click Channel Configuration Submit to submit the settings for the Acromag

8 Using Acromag Remote I/O with X-Series Paperless Recorders Solution Note 8 Input Average: Set average for 20 samples, click submit to set the Input Averaging Floating Point Control: (do not enable if reading integer format) - Select Enable Floating Point Support; submit - Select floating point byte order B1,B0,B3,B2, submit (this corresponds with Trendview s Modbus-X, FP B format and byte order) - Fill in the scaling values for the input range (example gpm) and submit Conclude by submitting all of the latest changes using the Channel Configuration Submit button

9 Using Acromag Remote I/O with X-Series Paperless Recorders Solution Note 9 Testing The Acromag s Test page shows real-time, live updates of the analog input signals and the scaled conversion values. These are the values which should appear when reading floating point values in the X-Series Recorder. X-Series Displays The X-Series pen values are set up as Communications values under the individual Pen Configurations as discussed previously. The pens that are enabled will be displayed on the recorder layout and will appear as DPM (digital) values, trend graph or bar graph values, depending on the selected screen layout.

10 Using Acromag Remote I/O with X-Series Paperless Recorders Solution Note 10 Communications diagnostics check The recorder Communications Diagnostics screen provides valuable information on whether the Modbus communications is taking place successfully. To view this diagnostic screen use the Path: Menu > Status > Diagnostics > Comms > Modbus; this will get you to the screen shown here. Conclusion/Summary The ability of the recorder to act as a Modbus Master simplifies the ability to get data into the recorder from remote devices via communications. Using communications, a Modbus slave device like the Acromag 967, enables the user to acquire and centralize the collection of data into a single device which can be networked to a higher level HMI if necessary.