Metek RCT 10 series, Installation And Operating Instruction

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RCT 10, 11, 12, 13 Series
62
6.5 RCT Series transmitter does not communicate with Drexelbrook
PC software
Is loop
current
between 3.7 and
22 mA?
Is there a
minmum of 250
ohms loop
resistance?
Are you connected
to a DCS?
Is It Polling?
Make it stop polling or power
transmitter from a separate
source - then re-check
operation.
Yes
Yes
Yes
Check:
1. Is correct
COM
Port selected at startup?
2. Is there any software running that would re-direct COM Port such as
Windows, mouse drivers, terminal emulation software, or TSR's.
(This can be tested by booting from Drexelbrook Calibration software in
the A: drive)
3. Possible bad RS-232 cable or defective modem.
4. Check modem connections to loop per loop drawing on
Figure 3-1.
5. Go to Section 5.6 to test transmitter.
Modem does
not
communicate
with
transmitter.
No
No
Start
No
Are you using
the Drexelbrook
supplied modem?
Check:
1. Is modem non-isolated
from ground and/or is your
laptop plugged into AC
power.? If so you may have
ground problem. Contact
Service department.
2. Some laptops don't provide
enough voltage to drive
modem correctly from
COM Port. Check with
modem supplier or try a
different laptop.
3. Checkout "Yes" response
tests listed below.
No
Yes
Check:
1. If current is greater than 22 mA disconnect at sensing
element and re-check. If current returns to normal,
check sensing element using checkout procedure in
Section 5.7. If current does not return to normal,
test transmitter with procedure in Section 5.6.
2. If loop current is 0 mA, check polarity of loop at
transmitter. If it is OK, check for open loop.
3. If loop current is between 0 and 3 mA transmitter is
likely bad. Test with procedure in
Section 5.6.
4. Check voltage at transmitter it should be at least 12
volts when 20 mA is flowing in the loop
5. Disconnect the three probe cable connections at
transmitter and retry. If it now communicates, check
cable and probe as described in
Sections 5.7 & 5.8.
No
Yes
1. Check Power Supply and loop source
resistance (the 250 ohms may be built in as
with the Drexelbrook 401-500 series or most
DCS inputs).
2. If not there add enough resistance for loop to
be at least 250 ohms.
1. Check calibrator connections to loop per loop drawing
Figure 4-1
.
2. Check for "noise" and ripple on loop with oscilloscope. Maximum noise level per HART
Foundation is 1.2 mV rms (500 - 10 kHz). Maximum ripple (47 - 125 Hz) specification is .2V p-p. Line
noise can sometimes be traced to things like motor speed controller wiring in close proximity with
transmitter. Noise can sometimes be overcome by increasing loop resistance thereby increasing
calibrator signal. Noise effects can also be reduced by connecting calibrator directly at
transmitter. Generally noise is only a problem when calibrator is communicating with transmitter
and does not affect normal operation of transmitter.
3. Check voltage at transmitter. It should be at least 12 volts when 20 mA is flowing in the loop.
4. If wiring is OK, go to
Section 6.6
to test transmitter.