Seametrics iMAG-Series - Manual (Page 13)

Page 11
INPUTS/OUTPUTS and OPERATION
Power
Source
Options
Installed
OID
Codes
Cable Conductor Usage
Red Black Green White Orange Blue
DC None DPTX DC PWR + DC PWR - Pulse + Pulse - 3.3V Comm TXD 3.3V Comm RXD
DC One Pulse, 4-20mA Output DPLX DC PWR + DC PWR - Pulse + Pulse - 4-20mA Out + 4-20mA Out -
DC One Digital Output DDDX DC PWR + DC PWR - Out 1 + Out 1 - Out 2 + Out 2 -
DC 4-20mA Output 1 Digital Output DDLX DC PWR + DC PWR - Out 1 + Out 1 - 4-20mA Out + 4-20mA Out -
DC One Pulse Output DPXX DC PWR + DC PWR - Pulse + Pulse - Do Not Connect Do Not Connect
AC None APTX Do Not Connect Signal Ground Pulse + Pulse - 3.3V Comm TXD 3.3V Comm RXD
AC One Pulse, 4-20mA Output APLX Do Not Connect Do Not Connect Pulse + Pulse - 4-20mA Out + 4-20mA Out -
AC One Digital Output ADDX Do Not Connect Do Not Connect Out 1 + Out 1 - Out 2 + Out 2 -
AC 4-20mA Output 1 Digital Output ADLX Do Not Connect Do Not Connect Out 1 + Out 1 - 4-20mA Out + 4-20mA Out -
AC One Pulse Output APXX Do Not Connect Do Not Connect Pulse + Pulse - Do Not Connect Do Not Connect
Control Cable Wiring
Pulse Output Connection. When the second OID code
character is “P”, refer to the “Digital Output Application”
diagrams on page 12 for recommended pulse output
connections to external equipment. Since this is an isolated
output, the external equipment must include a dc power
source to regenerate the pulse from the open-collector
output (transistor equivalent of a contact closure). A pull-up
or pull-down resistor may be needed if not included in the
user equipment as shown in the diagrams. Both the power
source and resistor may be supplied internally in some
types of control and monitoring devices. If not, as for most
PLC discrete input modules, they must be added externally
at the module input terminals. Pulse output rate in volume
units/pulse is user-settable via the SET P tab on the meter’s
setup menus.
Analog Output (4-20mA) Connection. When the second or
third OID code character is “L”, refer to the “Analog Output
Application” diagram on page 12 for 4-20mA current loop
output connections to external analog input devices. Since
the meter’s analog output is isolated and passive loop
power must be supplied externally as shown. (In addition, an
external resistor R
L
will be needed to convert the loop current
to voltage for voltage-only input devices.) The meter’s loop
transmitter minimum voltage drop is 6V which, with wiring
resistance and loop power supply voltage, will determine the
maximum resistance for R
L
. The flow rates corresponding to
4 and 20mA are user-settable via the SET 4 and SET20 tabs
on the meter’s setup menus.
Digital Output Connection. When the second or third OID
code character is “D”, refer to “Digital Output Application”
diagrams on page 12 for recommended connections to
external equipment. These outputs are essentially the same
as the Pulse Output described above except they are capable
of output frequencies up to 10kHz. Frequency output scaling
is user-settable via the FOUT tab on the meter’s setup menus.
Selections are: 500Hz and 1, 2, 5 and 10 KHz.
Cable Shield. In general, the cable shield and its bare drain
wire should be left unconnected at the user equipement end
of the cable to minimize “ground loop” problems.