Specifications

COMMAND SET
The D3000/4000 series uses a simple command/
response protocol for communication. A module must
be interrogated by the host to obtain data. A module
can never initiate a command sequence. A typical
command/response sequence could look like this:
Command: $1RD
Response: *+00075.00
A command is initiated with a command prompt, which
may be a dollar sign ($) or a pound sign (#). Following
the prompt a single address character must be trans-
mitted. Each module on a communications bus must be
setup with a unique address. In this case, the com-
mand is directed to module address ‘1’. The address is
followed by a two-or-three-character command which in
this case is RD for Read Data. The command is
terminated with a carriage return.
After module address ‘1’ receives the command it will
respond with the analog output data. The response
begins with a response prompt, which is an asterisk (*).
The data is read back in a standardized format of sign,
5 digits, decimal point, and 2 more digits. All D3000/
4000 modules represent data in the same standard
format.
Table 1 shows all of the D3000/4000 commands. For
each case, a sample command and response is shown.
Note that some commands only respond with an * as
an acknowledgment. For clarity, Table 1 separates
D4000 commands from the commands that are com-
mon to both the D3000 and D4000. Table 1 also
separates write protected commands from commands
that are not write protected.
For greater data security, options are available to echo
transmitted commands and to send and receive check-
sums. The # command prompt requests a response
message from the module that begins with an *,
followed by the channel address, command, data (if
necessary) and checksum. This response echoes the
channel address and command for verification and
adds checksum for error checking. Checksum is a two
character hexadecimal value that can be added to the
end of any command message, regardless of prompt,
at your option. Checksum verifies that the message
received is exactly the same as the message sent.
The D3000/4000 performs extensive error checking on
commands and responds with an error message if
necessary. All error messages start with an error
prompt (?) followed by the channel address and the
error description. In the following example, the D3000/
4000 does not recognize ‘AB’ as a valid command.
Command: $1AB
Response: ?1 COMMAND ERROR
Table 1 D3000/4000 Command Set
Command Definition Typical Typical
Command Response
Message Message
D3000/4000 Commands
ACK Acknowledge $1ACK *
AO Analog Output $1AO+00020.00 *
DI Digital Input $1DI *0007
HX Hex Output $1HX0FFF *
RAO Read Analog Output $1RAO *+00017.50
RD Read Data $1RD *+00012.34
RHI Read High Limit $1RHI *+00020.00
RID Read Identification $1RID *BOILER
RLO Read Low Limit $1RLO *+00000.00
RMS Read Manual Slope $1RMS *+00004.00
RMX Read Maximum $1RMX *+00020.00
RMN Read Minimum $1RMN *+00000.00
RS Read Setup $1RS *31070140
RSU Read Setup $1RSU *31070140
WE Write Enable $1WE *
The following D3000/4000 commands are Write Protected
HI High Limit $1HI+00015.00 *
ID Identification $1IDBOILER *
LO Low Limit $1LO+00004.00 *
RR Remote Reset $1RR *
SU Setup $1SU310701C0 *
TMX Trim Maximum $1TMX+00020.17 *
TMN Trim Minimum $1TMN+00000.95 *
D4000 Commands
RAD Read Analog Data $1RAD *+00012.34
RPS Read Present Slope $1RPS *+00001.00
RSL Read Slope $1RSL *+00001.00
RSV Read Starting Value $1RSV *+00005.00
RWT Read Watchdog Timer $1RWT *+00010.00
The following D4000 commands are Write Protected
MS Manual Slope $1MS+00001.00 *
MX Maximum $1MX+00100.00 *
MN Minimum $1MN-00025.00 *
SL Slope $1SL+00001.00 *
SV Starting Value $1SV+00004.00 *
TRX Trim Readback Maximum $1TRX *
TRN Trim Readback Minimum $1TRN *
WT Watchdog Timer $1WT+00010.00 *
WSL Write Slope To EEPROM $1WSL+00100.00 *