Laurel Electronics LTM DPM SERIES ANALOG INPUT, SERIAL DATA OUTPUT User Manual
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Values are transmitted in a continuous string with no intervening spaces. If the 5th digit in is
set to 1 using Instrument Setup software, the termination characters of
once at the end of the string. In either case, if included, the coded character appears at the end
of the last value only.
3.0
NETWORK CONFIGURATIONS
Using the Custom ASCII protocol, TM Series transmitters can operate in a point-to-point mode
using RS232 or RS485, or in a multi-point mode using RS485.
The point-to-point mode is a direct connection between a computer (or other digital device)
and the transmitter. An device address can be selected; however, it is suggested that address 1
be selected as a standard for the point-to-point mode.
The multi-point mode is a connection from a host computer to a multiplicity of transmitters
bused together with their inputs and outputs connected in parallel. For long cable runs, the last
device should have a termination resistor installed. It is necessary to set up each device on the
bus with a different address from 1 to 31. To command a particular device, its address is used
in conjunction with the command, and only that device responds. The outputs of all of the
devices on the bus are set to a high impedance state, except the device being addressed. The
device addresses range from 1 to 31, with 0 being a special address to which a meter responds
only internally (e.g. Reset), but does not transmit any response on the output lines. All devices
may be commanded simultaneously with a 0 address, and there will not be any output
response contention. Addressing of transmitters can be set with Instrument Setup software.
4.0 COMMAND MODE OVERVIEW
Using the Custom ASCII protocol, TM Series transmitters operate in the Command Mode only.
In this mode, the device does not send data automatically, but responds to commands received
from a host computer. These commands can be:
• To transmit the latest or peak measurement
• To reset the meter completely or just the peak value and/or latched alarms
• To display a value sent from the computer
• To transmit present setup parameters
• To receive new setup parameters,
• To monitor or alter data in selected memory locations of the meter.
5.0 COMMAND MODE FORMAT
CHAR 1 - Command Identifier
All commands begin with “*” followed by the meter address, then a command letter
followed by a sub-command number or letter. Additional characters may be append-
ed. All commands terminate with