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SECTION 19 – PORT 2 SERIAL COMMUNICATION
Port 2 Protocol Formats.
PROTOCOL
TYPE
BAUD RATE
START BIT PARITY BIT
STOP BIT
PROG RS232
38400
1
EVEN
1
MODBUS RTU
RS232
38400
1
EVEN
1
MODBUS
RTU
RS232
9600 1 NONE 1
GPS WF1
RS232
19200
1
EVEN
1
PROG
Port is available for programming function only.
MODBUS RTU
Note: If port is set for a protocol other than programming i.e. dual function then button
2 on the front of the interface card should be used to toggle between functions – Refer
to configuration manual for more details
.
Modbus RTU Protocol
RTU tables.
Each character represents 8 bit binary data in hexadecimal
format.
Y
represents a character with more than one possible value.
TIME
represents elapsed time of 3 ½ characters min
.
Read Request – Master
START
SYSTEM
ADDR
FUNC
START
ADDR
HI
START
ADDR
LO
NO. OF
INPUTS
HI
NO. OF
INPUTS
LO
LRC
ERROR
CHECK
STOP
TIME Y
0x01
Y
Y
Y
Y
YY
TIME
System address
Range is 0x00 (0) to 0xFE (254). Default is 0x00.
Start address HI/LO word
Indentifies first data bit to be read. The data type returned for this address depends on
a number of factors. Standard systems supplied before August 2011 can only return
contact data in the range 0 to 1984:-
Address of first bit = Start address.
Address 0 will contain contact data for inputs 1.
Address 1 will contain contact data for inputs 2.
