Startco MPU-16A

Problem Solution Overview

We performed testing between the subject device and our 3100-MCM product.

Solution Brief

Our testing generated the following results:

• We were able to successfully communicate with the device. (see below for configuration parameters used during the testing)
• The product supported Modbus functions 1,3,6 & 16

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:

The product testing was perfomed with the following settings used.

- Baud: 9600
- Parity: None
- Stop: 1
- Mode: RTU Master Mode
- Physical Connection : RS-485

The Module Configuration used in our testing was as follows:

This configuration, in combination with the example ladder logic referenced below, generates the following memory map:

N10:0 to N10:129 - Slave Data
N10:130 to N10:149 - Slave Error Table (Contains revision level information also)
N10:150 to N10:199 - Master Error Table (Contains status of commands for diagnostics)

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

Our test command list perfoms the following functions.

1. N7:50 Read registers 40001 - 40018
2. N7:60 Read registers 40025 - 40043
3. N7:70 Write to register 40003 (see comments)
4. N7:80 Write to register 40003 (see comments)

Cable Connection:

The physical connection which was used during testing was as follows:

Additional Comments and Observations:

The Modbus function 16 supports a maximum length of 1 word in this unit.

1. All writes to the unit will require 300 ms before another write may be processed. In the test setup this was accomplished by using a 300 ms RTS ON delay.