Doran 2200 Series, Инструкция по эксплуатации

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RS485 Option Specification
Maximum Cable length 4,000 ft.
Maximum number of scales per bus 32 nodes
Maximum Number of Print commands that
can be stored in Print Buffer (2000 bytes) 130 with Print Output
format = "
FO
"
Bus common mode range +7 volts
RS485 node load impedance 12K ohms
Table 11: RS485 Option Specification
RS485 Commands
In order to communicate with your scale, your bus controller must send the scale
commands in a format it expects. The scale's communications string is constructed as
follows:
01 <SC> <CR>
Where; "01" is the scale bus address (01 to 99)
<SC> are the scale commands.
<CR> Carriage Return is a ASCII character (0x0d hex or ^M)
Example: "01W " Initiates a print command that will store data to the Print Buffer at
address 01.
It is possible to broadcast a command to all scales on the RS485 bus by using scale bus
address “00”. All scales will receive this command and will respond.
Warning: Do not
use this command to dump the contents of the scale buffer as all the scales on the bus
will attempt to communicate at once and will result in the loss of data.
All scale commands as laid out in the Data Communications section, Table 2 are
available for use in RS485 communications. The following are some common
commands recognized by the scale:
W Instructs the scale to print to the print buffer.
Z Instructs the scale to perform a "ZERO" operation.
D Instructs the scale to dump (or transmit) the Print Buffer's contents to the
bus. The Print Buffer is then cleared of all data.
Bus termination resistors
Since RS485 systems are designed to cover long distances, it is often necessary to
terminate the bus at its ends. This termination reduces reflections on the bus and
provides a pull up for the bus drivers. The RS485 option board has these termination
resistors built in and jumper accessible. Table 12 provides terminator resistor jumper
information.