Dwyer DPW - Manual (Page 18)

7. RS-485/RS-232 SOFTWARE INTERFACE COMMANDS
7.1 - General
The standard DPW comes with an RS-485 interface. For the optional RS-232
interface, the start character (!) and two hexadecimal characters for the address
must be omitted. The protocol described below allows for communications with the
unit using either a custom software program or a “dumb terminal.” All values are
sent as printable ASCII characters. For RS-485 interface, the start character is
always (!). The command string is terminated with a carriage return (line feeds are
automatically stripped out by the DPW). See Section 2.2.5 for information regarding
communication parameters and cable connections.
7.2 - Commands Structure
The structure of the command string:
!,,Arg1,Arg2,Arg3,Arg4
Where:
!
Start character **
Addr RS485 device address in the ASCII representation of
hexadecimal (00 through FF are valid).**
Cmd The one or two character command from the table below.
Arg1 to Arg4 The command arguments from the table below.
Multiple arguments are comma delimited.
CR Carriage Return character.
** - OMIT FOR RS232 INTERFACE.
Several examples of commands for RS-485 option follow. All assume that the DPW
meter has been configured for address 18 (12 hex) on the RS485 bus:
1. To get a flow reading: !12,F
The device will reply: !12,50.0 (Assuming the flow is at 50.0% FS)
2. To get current Flow Alarm status: !12,FA,R
The device will reply: !12,FA,N
(Assuming no alarm conditions)
3. To get a Main Totalizer reading: !12,MT,R
The device will reply: !12,MT:93.05
(Assuming the Main totalizer reading is 93.5)
4. Set the flow high alarm limit to 85% FS flow rate:
!12,FA,H,85.0
The device will reply: !12,FA,H:85.0
Several examples of commands for RS-232 option follow.
1. To get a flow reading: F
The device will reply: 50.0
(Assuming the flow is at 50.0% FS)
2. To get current Flow Alarm status: FA,R
The device will reply: FA,N >
(Assuming no alarm conditions)
3. To get a Main Totalizer reading: MT,R
The device will reply: MT:93.05
(Assuming the Main totalizer reading is 93.5)
4. Set the flow high alarm limit to 85% FS flow rate:
A,H,85.0
The device will reply: FA,H:85.0 >
Command
Name
Flow
Temperature
**
Diagnostic
Events
Diagnostic
Mask
Meter Info
Description
Requests the current flow sensor
reading in current EU.
Requests the current temperature
reading in current EU (°C or °F).
Read/reset current status of
Diagnostic Events log register.
Display/Set Diagnostic Events
mask register.
See list of the Diagnostic Events
below.
Requests meter configuration
info:
- full scale range (L/min)
- RTD option support(Y,N)
- Analog Flow Output
configuration (V,C)
- Analog Temp. Output
configuration (V,C)
No.
1
2
3
4
5
Command
F
T
DE
DM
MI
Argument 1
No Argument
(read status)
R (reset Event Log
register to 0x00)
No Argument
(read current
Diagnostic Events
Mask register)
0x0000 to 0xFFFF
Note: All 6
characters are
required.
Argument 2 Argument 3 Argument 4 Response
(Actual flow in
current engineering
units)
(Actual temp.
in current engineering
units)
DE:0x10
0x10 - diagnostic word
(16 bits wide)
DE: 0x0
DM: 0x9FFF -
diagnostic mask (16 bits
wide).
Set bit - Enable
Clear bit - Disable
DM: 0x9FFF
MI: 18.92706,Y,V,V
Y - RTD support
N - No RTD support
V - 0 to 5 VDC output
C - 4 to 20 mA output
7.3 ASCII Commands Set
DPW METER ASCII SOFTWARE INTERFACE COMMANDS
Note: An * indicates power up default settings.
An ** indicates optional feature not available on all models.
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