Yokogawa DX 100/200

Problem Solution Overview

We performed testing between the subject device(s) and the ProSoft Technology MVI56-MCM product.

Solution Brief

Our testing generated the following results:

• We were able to successfully communicate over Modbus RTU mode with the device. (See below for configuration parameters used during the testing)
• The product supported Modbus functions 3, 4, 6, 8, and 16. The device tested supported 16-bit integer and unsigned integer read commands. The test used Function Code 4 only.
• Procedure used the sample MVI56-MCM ladder logic using RSLogix 5000 Version 10.0. No changes to the sample ladder or data tables were made.
• 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.

PURPOSE

Verify Modbus RTU communication between ProSoft MVI56-MCM and Yokogawa DX208 for Measurement Channels 1-8 and Math Channels 31-38 (unsigned) using two-wire RS-485 connection between devices.

EQUIPMENT

ProSoft MVI56-MCM communication module

Yokogawa DX208 -1 -2 /AR2 /C3 /M1with serial RS-485 communication.

Configuration:

The product testing was performed with the following settings used for the MVI56-MCM and DX208 device.

ProSoft Model 1454-9F 9-pin screw terminal adapter used on MVI56-MCM Port 2

RS-485 Configuration

- Slave Address 1
- Baud 9600
- Data length 8
- Start/Stop Bits 1
- ParityNone

RS-485 Cabling

When the RS-485 interface is used, a single two or three wire cable is required. The use of the ground is optional and dependent on the RS-485 network. The cable required for this interface is shown in the following diagram:

Terminating resistor was not installed during the test.
MCM Port 1 Controller Tags

The default MCM ladder controller tags for Modbus Port 2 setting used are displayed in the following: (Port 1 setting are used for the configuration/debug port)

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The DX208 unit configuration was preset from the factory to the following:

Communication Setup
- RS-232 Hand shaking:Off:Off
- RS-422/485 Address: 1
- Protocol: Modbus

The following command list shows commands, which were used to test the communications:

The test used all of the default settings found in the sample ladder logic.

The module controller tag definitions are:

[MCM Port 1 Command List] (Port 1 and Port 2 represented in the module configuration/debug using Hyper Terminal displayed below, represent Port 2 and Port 3 respectively on the module and ladder Controller Tags)

The DX208 register assignments with Modbus addressing for each MVI command above are defined below as follows:

Note: DX208 requires zero-based addressing, so all address found in the commands above are offset by one address.

MCM.P2Cmd(0) and MCM.P2Cmd(1) tag configuration

Our test command list performs the following functions.

1. Read Measured data of CH01-CH08 value (Function Code 4)
- Function code4
- Slave Address 1
- Starting register address0 (decimal zero-based for 30001)
- Number of registers8
- Type integer
- Swap Code0
- Expected observation read Ch01-Ch08 to MVI database address 600-607 or Controller Tags MCM.ReadData(0-7)

2. Read Computer data of CH31-CH38 value (Function Code 4)
- Function code4
- Slave Address 1
- Starting register address2000 (decimal zero-based for 32001)
- Number of registers16 (upper and lower bytes for 8 channels)
- Type unsigned integer
- Swap Code1 (words are swapped)
- Expected observation read Ch31-Ch38 to MVI database address 608-623 or Controller Tags MCM.ReadData(8-23)

Both test commands are enabled for continuous read of channel information with EN set to 1in the above commands.

Performing the above test 1 the channel data was read into the controller tags.

Performing the above test 2 the channel data was read into the controller tags.