Siemens SITRANS 7ME3500, Operating Instructions Manual, Page: 82 / 296

Connecting
5.5 Sensor Installation
FUE1010 IP65 NEMA 4X
80
Operating Instructions, 12/2014, A5E03086491-AC
Actual Zero
The Actual Zero function simply averages the indicated "zero flow" readings (over a user
defined time period) then stores this average value in memory. Under normal operation the
indicated flow reading is zero compensated by simply subtracting this memorized value from
the uncompensated flow reading. Actual Zero is the most positive method for zeroing the
system; however, flow must be stopped with the line blocked (if possible) before invoking this
function. If stopping flow is not possible then an alternate zeroing method should be
selected.
ReversaMatic
This routine involves swapping the Up and Down sensors on the pipe (while keeping the
cables attached) such that the difference in the transit-time change represents the zero
offset. The fixed zero offset value is stored in memory in the same manner as described in
Actual Zero. This routine would generally be used whenever flow cannot be stopped and the
sensors cannot be mounted in the Reflect Mode configuration. Flow must be stable during
the entire process.
ZeroMatic
When ZeroMatic is invoked the flow meter first performs the same analysis as described
above in the AutoZero routine. However, after this analysis is complete the flow meter
continues to interrogate the pipe wall signal and update the zero offset value under normal
operation, such that the flow meter dynamically compensates for changing conditions which
would normally result in zero drift. ZeroMatic will only operate with the sensors mounted in
the Reflect Mode configuration and is recommended for applications which experience large
temperature extremes.
Note
Invoking ZeroMatic will clear any existing "fixed" or memorized zero offset. If any zero offset
remains after flow is stopped, an Actual Zero can be performed without interrupting
ZeroMatic operation. To disable ZeroMatic, invoke it again, but then press <Left Arrow> to
abort the installation.
Note
The ZeroClr command only resets the memorized zero offset registers not those set when
the AutoZero routine is invoked.
Using Actual Zero
Note
Flow must be stopped with the line blocked (if possible) before invoking this function.