Programming Guide
Marathon MM
77
10.10
RS485 Communication
The serial RS485 communication can be either in 2-wire or 4-wire mode.
HM=2
sets the sensor into 2-wire communication mode.
HM=4
sets the sensor into 4-wire communication mode
For setting the baud rate, one of the following two commands must be selected.
D=576
sets the baud rate to 57600, baud rate must be given with 3 numbers (003, 012, 024,
096, 192, 384, 576, 115).
BR=57600
sets the baud rate to 57600, baud rate must be given with up to 6 numbers (300, 1200,
2400, 9600, 19200, 38400, 57600, 115200)
In case of using the sensor in 2-wire mode the baud rate is limited to 38400.
10.11
Multidrop Mode
Up to 32 devices can be connected within an RS485 multidrop network, see section 6.4
page 32. To direct a command to one sensor among the 32 possible, it is necessary to
“address” a command. Therefore, a 3
-digit number is set prior the command. The 3-digit number is
determined between 001 and 032. A unit with the address 000 is a single unit and not in multidrop
mode.
XA=024
sets the device to address 24
Changing an address:
(e.g., the address is change from 17 to 24)
command
answer
“017?E”
“017E0.950”
// asking one sensor on address 17
“017XA=024”
“017XA024”
// setting of a new address
“024?E”
“024E0.950”
// asking same sensor now on address 24
If a command is transferred, starting with the 3-digit number 000, all units (with addresses from 001 to
032) connected will get this command - without to send an answer.
command
answer
“024?E”
“024E0.950”
“000E=0.5”
will be executed from all sensors, no answer
“024?E”
“024E0.500”
“012?E”
“012E0.500”
When a sensor has a multidrop address between 001 and 032, its control panel is
automatically
locked. It can be unlocked with the command “xxxJ=U”, where xxx is the
multidrop address!
