78
SECTION 18 – PORT 1 SERIAL COMMUNICATIONS
Port 1 Protocol Formats.
PROTOCOL
TYPE
BAUD RATE
START BIT PARITY BIT
STOP BIT
RTK AMS
RS485
38400
1
EVEN
1
Modbus RTU
RS485
38400
1
EVEN
1
Modbus
RTU
RS485
9600 1 NONE 1
Modbus RTU
RS485
9600
1
EVEN
1
AMS Time Stamped Event Protocol
Refer to RTK Instruments for technical assistance
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.
Address 254 will contain contact data for inputs 255.
Address 255 will contain contact data for inputs 256.
Etc.
Bespoked systems supplied before August 2011 may have additional data types
available, please contact RTK for specific information / manual.
