Westronics SM100 Smart Multiplexer
Problem Solution Overview
We performed testing between the subject device and our 3100-MCM (Rev 2) 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 1,2,3,4,5,6,15 & 16
- Message turn around for this unit averaged 35 ms
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:
Port : Westronics Ports 1 and 2 were both tested (Port 2 is fixed at 9600 baud, 8 N 1, RTU Mode)
- Baud : 19200 (Port 1 Only)
- Parity : None
- Stop : 1
- Mode : RTU Mode (ASCII Mode available but not tested)
- Physical Connection : RS-485 (2 wire connection)
The Module Configuration used in our testing was as follows:
The Westronics unit was tested using MCM Rev 2.0. There may be minor configuration differences if you are using Rev 1.4x :
|
Address
|
0
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
|
N7:0
|
0
|
0
|
6
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
N7:10
|
0
|
0
|
6
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
N7:20
|
4
|
1
|
2
|
130
|
150
|
0
|
0
|
0
|
4
|
0
|
This configuration, in combination with the example ladder logic referenced below, generates the following memory map:
N10:0 to N10:129 - Slave Response Data
N10:130 to N10:149 - Slave Port Error Table (Contains revision level information also)
N10:150 to N10:199 - Master Error Table (Contains status of commands for diagnostics)
Command List:
The following command list shows some of the commands which were used to test the communications:
|
Address
|
0
Port
Number
|
1
Slave
Number
|
2
Function
Code
|
3
Source
Address
|
4
Count
|
5
Dest.
Address
|
6
Read
Type
|
|
N7:50
|
1
|
1
|
3
|
4009
|
50
|
0
|
0
|
|
N7:60
|
1
|
1
|
3
|
9
|
10
|
50
|
0
|
|
N7:70
|
1
|
1
|
6
|
200
|
1
|
4009
|
0
|
|
N7:80
|
1
|
1
|
16
|
210
|
10
|
4019
|
0
|
|
N7:90
|
1
|
1
|
1
|
0
|
160
|
60
|
0
|
The commands which were tested perfomed the following functions ( Remember that an offset of 1 is required to compensate for the fact that Modbus addressing begins at 1 and A-B/ProSoft addressing begins at 0) :
- N7:50 Reads the point configuration information for Points 010 to 014 from 4010. Ten words are provided per point, requiring a read lenght of 10 words per point
- N7:60 Reads 'Data Scaled to Engineering Units' for Points 010 to 019 from 10 to 19 in the Westronics unit.
- N7:70 Writes to the configuration 'Input Type Code' for Point 010. This is a single word write command
- N7:80 Writes an entire point configuration (10 words) for Point 011.
- N7:90 Reads binary data using a FC 1 command.
Cable Connection:
The physical connection which was used during testing was as follows:
|
MCM Module
|
|
Device
|
|
TXDRXD + (14)
|
--------------------------
|
Pin (+)
|
|
TXDRXD - (25)
|
--------------------------
|
Pin (-)
|
|
RTS
|
-----------|
|
Jumper between RTS/CTS
|
|
CTS
|
-----------|
|
on module must be installed
|
|
GND
|
|
No Connect on GND
|
For ease of installation, termination on the ProSoft module was accomplished using our screw termination adaptor for the DB-25 plug. A similar screw termination plug is also available for the DB-9 required for the 3150-MCM.
The part number for these is:
1451-9F : DB-9 to RS-422/RS-485 Screw Terminals (for 3150-MCM)
1452-25M : DB-25 to RS-422/RS-485 Screw Terminals (for 3100-MCM)
Additional Comments and Observations:
- This unit was very simple to get on-line and appears to follow conventional Modbus specifications.
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