Function Expansion Unit FE260
Elster-Instromet GmbH
33
B-5 Serial data interface to the volume corrector
Intrinsically safe RS-485 interface for four-wire operation
Designation .......................... “R” (received data), “T” (sent data)
Cable connection ................. Screw
terminals, blue
Cable cross-sectional area .. 0.5...1.5 mm²
Fit wire-end sleeves to flexible stranded wires
Cable length ........................ 1000 m max.
depending on transmission speed (see
below)
Screening ............................ Connect cable screen to the cable gland over the full area
Transmission speed
for cable length
up to 500 m.............. 19200 Bd max.
up to 1,000 m.............. 9600 Bd max.
Safety limits ......................... (see Declaration of Conformance A-2)
B-6 Digital outputs
Individually electrically isolated transistor outputs (open collector)
Designation .......................... “A1”, “A2”, “A3”, “A4”
Cable connection ................. Screw terminals, green, for
- solid wires
0.14...2.5 mm²
- flexible wires
0.14...1.5 mm²
Fit wire-end sleeves to flexible stranded wires
Screening ............................ Connect cable screen to the cable gland over the full area
Switching voltage ................. 30 V max.
Switching current ................. 50 mA max.
Voltage drop ........................ 1.5 V max.
Residual current ..................
0.01 mA max.
Frequency
A1, A3, A4 ................... 10 Hz max. for cable length up to 10 m *
A2
................................
500
Hz
max.
for cable length up to 10 m *
and 40 to 50 mA switching current **
* With a cable length of more than 10 m between the FE260 and the volume corrector
(intrinsically safe electrical circuit) the maximum frequency cannot be guaranteed. (See
B-4 and Chapter 0).
** With a smaller load (lower switching current) the frequency which can be transmitted is
reduced.
In this case a resistance can be wired in parallel to the load so that in total a switching
current of approx. 40 to 50 mA (no more) is produced. The resistance should have a
rating of 2 watts or higher.
Note that the switching current at frequencies above approx. 1 Hz cannot be measured
with a commercially available ammeter (multimeter). You can connect an ammeter to
the input of the device which is to be later connected to the FE260 to determine the
switching current.
