Measuring Inputs And Additional Channels - Ahlborn ALMEMO 2590-2 Operating Instructions Manual

7. Connecting the sensors / transducers
tended disconnection if the cable is accidentally pulled. To withdraw the con-
nector, both these levers must be pressed in at the sides.
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Splash-proof variants of devices in the ALMEMO 2590 series are also avail-
able as options. For this purpose a number of new sensors are now available
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with spray-coated ALMEMO connectors incorporating a double sealing lip
specially designed to protect the socket unit against the effects of penetration
by splashing water. For any unused sockets protective stoppers are available.

7.2 Measuring inputs and additional channels

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The ALMEMO 2590-2/3/4 measuring instruments incorporate respectively 2,
3, or 4 input sockets (1) to which initially measuring channels M0 to M1/M2/M3
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are allocated. However, ALMEMO sensors can, if required, provide up to 4
channels with 4 input sockets each so that altogether 16 channels are avail-
able. The additional channels can be used in particular for humidity sensors
with 4 measuring variables (temperature / humidity / dew point / mixture ratio)
or for function channels. Each sensor can if necessary be programmed with
several measuring ranges or scaling settings; and 2 or 3 sensors, if pin assign-
ment so permits, can be combined in a single connector (e.g. rH / NTC, mV /
V, mA / V, etc.). The additional measuring channel numbers per connector go
up in steps of 10 (e.g. the first sensor has channels M0, M10, ... and the second
sensor has channels M1, M11, .... etc.).
Device-internal channels
A further innovation on devices in this series is the 4 additional device-internal
channels, these are the next after the last available socket. The first of these is
programmed by default as differential channel M1 – M0. This only applies,
however, if there are two sensors with the same units and same decimal point
position connected at measuring points M0 and M1. The fourth (M32/M33/M34,
depending on type) is used temporarily for the purposes of averaging (see
11.2). However, all 4 channels can be programmed with any other function
channels (e.g. U-Bat, cold junction compensation, averages, volume flow,
etc.); (see 12.10, Manual Section 6.3.4).
The advantage of device-internal channels is that when using several sensors
for the same application these sensors do not have to be reprogrammed and
can be exchanged without losing the function channels. However, if the whole
application operates with just one sensor, then programming on the sensor it-
self makes more sense.
This, depending on device type, gives the following channel assignments :
16 ALMEMO ® 2590