10. RS 485 ( ModBus ) Output :
This
supports MODBUS (RS485) RTU protocol( 2-wire ) .
instrument
Connection should be made using twisted pair shielded cable. All "A" and "B" connections
are daisy chained together. The screens should also be connected to the “Gnd” terminal.
To avoid the possibility of loop currents, an Earth connection should be made at one point
on the network.Loop (ring) topology does not require any termination load. Line topology
may or may not require terminating loads depending on the type and length of cable used.
The impedance of the termination load should match the impedance of the cable and be at
bothends of the line. The cable should be terminated at each end with a 120 ohm
(1/4 Watt min.) resistor.
RS 485 network supports maximum length of 1.2km. Including the Master, a maximum of 32
instruments can be connected in Rs485 network.The permissible address range for the
is between 1 and 247 for 32 instruments. Broadcast Mode (address 0) is not allowed.
instrument
The maximum latency time for the
is 200ms i.e. this is the amount of time that
can pass before the first response character is output.
instrument
After sending any query through software ( of the Master) , it must allow 200ms of time to
elapse before assuming that the
is not going to respond. If slave does not
respond within 200 ms, Master can ignore the previous query and can issue fresh query
to the slave.
instrument
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Summary of Contents for mfm 3480
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