Vegalog COM557
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 3 & 4.
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: 38400
- Parity: None
- Stop: 1
- Mode: RTU Master Mode
- Physical Connection : RS-485
The Module Configuration used in our testing was as follows:
|
Address
|
0
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
|
N7:0
|
0
|
0
|
7
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
N7:10
|
1
|
1
|
7
|
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 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)
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
|
0
|
40
|
0
|
0
|
|
N7:60
|
1
|
1
|
4
|
0
|
40
|
40
|
0
|
Our test command list perfoms the following functions.
- N7:50 Read 40 registers from Vegalog com 557 with function 3.
- N7:60 Read 40 registers from Vegalog com 557 with function 4.
Cable Connection:
The physical connection which was used during testing was as follows:
RS485 Connection
|
3100-MCM
Module
|
|
Vegalog
COM557
|
|
14 TxRxD+
|
-----------------------
|
/RX
|
|
25 TxRxD-
|
-----------------------
|
RX
|
|
4 RTS
|
-----------|
|
|
|
5 CTS
|
-----------|
|
|
RS422 Connection
|
3100-MCM
Module
|
|
Vegalog
COM557
|
|
14 TxD+
|
-----------------------
|
/RX
|
|
25 TxD-
|
-----------------------
|
RX
|
|
16 RxD+
|
-----------------------
|
/TX
|
|
18 RxD-
|
-----------------------
|
TX
|
|
4 RTS
|
-----------|
|
|
|
5 CTS
|
-----------|
|
|
RS232 Connection
|
3100-MCM
Module
|
|
Vegalog
COM557
|
|
2 TxD
|
-----------------------
|
RXD
|
|
3 RxD
|
-----------------------
|
TXD
|
|
7 GND
|
-----------------------
|
GND
|
|
4 RTS
|
-----------|
|
|
|
5 CTS
|
-----------|
|
|
Additional Comments and Observations:
- Tested baud rates were 300, 9600 and 38400 baud.
- RTS/CTS must be jumpered on the 3100-MCM module for correct operation.
- Connection diagrams for RS485, RS422 and RS232 are provided above.
- When accessing registers from the VEGALOG COM 557 using the LOGBUS backplane each data value consumes 4 bytes with the data being returned in the odd numbered registers. Even numbered registers contain a status value that can be used to determine the validity of the data value. Possible values are 0H (value valid), 80H (value not available) or FFH (general failure)
|
