Problem Solution Overview
We performed testing between the subject device and the ProSoft Technology MVI56-MNET product residing in a Controllogix rack with processor.
Solution Brief
Our testing generated the following results:
- We were able to successfully communicate over Modbus TCP/IP with the device. (See below for configuration parameters used during the testing)
- The product was tested using Modbus functions 3 and 16. The device tested supported read and write commands.
- Procedure used the sample MVI56-MNET ladder logic using RSLogix Version 8.02. A ladder file was created to perform some data conversion on the date values.
- The purpose of our testing is to assure a level of compatibility in the communications between the two products. Through this testing, we attempt to identify problem areas that may arise when implementing the interface in the field.
CONFIGURATION:
Nexus 1250
The device was checked for its communication settings and was setup for Modbus TCP/IP using the supplied Nexus Communicator software. The module was initially setup using serial communication to edit the profile for the TCP RJ-45 option. Setup can be accomplished using either the serial or RJ-45 ports. We wanted to determine if the device could be setup from either port of communication. Serial communication used the modules default settings and the TCP port's IP address was changed to accommodate our network-addressing scheme.
Serial Port Settings:
A straight through cable was used from the PC to the Nexus (RS-232) Port 1. This port was used to setup the Nexus module of Modbus TCP communication. The following displays Port 1 settings used for setup.
Pressing the ADD button allowed two locations to be added, RS-232 and TCP communications. (RS-232 for initial module setup and TCP for MVI56-MNET communication.)
The following screen shows the RS-232 location settings created.
The following screen shows the RJ-45 location Ethernet TCP/IP settings used for the Nexus Communicator and the MVI56-MNET module.
After the two locations have been added connect to the module using the Connection Manager. Press CONNECT button and select RS-232 location. This was done initially to set the IP address of the module.
The following screen appears. Select CONNECT button to connect to the device.
The following screen appears. Select OK button to begin communications
Select EDIT PROFILE button. The Device Profile Window will display.
Double click on the Serial Port 1 item above to display the access to the IP address of the unit. The following screen will appear. In the Network section change the IP address required for your network.
After communication setup is established, scroll down to the Custom Modbus Map item and select by double clicking the item.
The following window will display without the filled in Modbus addresses.
Enter the Line and Point number to be mapped. The Nexus software will automatically fill in the remaining information for this item. The Modbus Protocol & Register Map Revision 1.18 can be downloaded from EIG WEB site: http://www.electroind.com/pdf/NxModbusE107708118.pdf.
The example Nexus Profile configuration file above was saved and can be downloaded from our WEB site . The sample MVI56-MNET.cfg and sample Controllogix ladder logic for this test procedure is also provided under the downloads section.
A total of 50 registers are read from the above table into the Controllogix data objects using a single command within the MVI56-MNET module.
After all the values have been entered into the map select Update Device. This will take a few seconds for the program to burn the firmware.
This completes the Nexus 1250 configuration requirements.
MVI56-MNET configuration
Using a terminal emulator such as Windows HyperTerminal, setup communication with the MVI module. The procedures are outlined in a separate manual available from our WEB site or CD-ROM. Transfer the configuration file MNET.cfg to the MVI module.
The commands issued to the client located in the MNET Client 0 commands area are as follows:
The addressing used is zero-based for the MVI module. The modules revision level used at the time of testing is as follows:
This concludes the MVI56-MNET module setup.
Controllogix sample ladder Configuration
Generally speaking the sample ladder logic provided was not modified. However, to convert data into a legible format, a ladder file was added to convert the Current Time data for the read and write operation as follows:
Two data objects to are added to allow for time date data (word to byte) conversion. NexusCurrentTime are the values read from the Nexus 1250 and NexusNewCurrentTime allow the Nexus module to be updated with a new time and date
The structure for the NexusCurrentTime and NexusNewCurrentTime is as follows:
With the exception, NexusNewCurrentTime contains 2 additional words for the Day of Week value.
The data is read into the Controllogix Mnet1.ReadData data objects directly from the MVI56-MNET prior to conversion. Mnet1.ReadData[4] to [7] contains Current Time data from Nexus. For example, the Mnet1.ReadData [4] 2-byte word contains the Century and Year data.
Our test command list performs the following functions.
- Read the values of the 50 input registers within the Nexus unit. This command READ 412889-412938 (4 is assumed) mapped registers into the MVI56-MNET database starting address 200.
- Write the values of the 5 output registers in the unit. This command WRITES to Nexus module 00085-00089 (NexusNewCurrentTime [0]-[4] copied under program control to Mnet1. WriteData(0-4)) registers from MVI56-MNET starting database address 0. The new date and time were entered manually and sent to the Nexus controller by toggling the NewTime bit.
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