KROHNE BM 70 A_P EN - Manual (Page 13)

Installation and operating instructions BM 70 A/P Page: 13 11/00
•
Since signal reflections at the line ends can interfere with Communication, both the line beginning
(at the computer system) and the line end (at the last device) should be terminated with the typical
surge impedance of the cable (120
Ω
). To do this inside the BM 70 A/P: see Section 7.9.
4.7 Breakdown signal
Breakdown information can be called up via the following interfaces:
•
Local display: flashing display, plain text information
•
Current output: error signal 2 mA (Exi = 3.6 mA) or 22 mA
•
Switching output: contact opens or closes
•
Digital interfaces: interrogation of error flags
4.8 Digital input
The digital input (for electrical data: see Section 4.2) can be used for temporarily "freezing" measure-
ments or for carrying out a hot start. It is only available in the "Ex-e current output HART
®
" version.
The "freeze" function can be used to blank out larger, temporary interferences, e.g. very slow agitator,
slide gate, ball valve in the stilling well. The last measured values in each case are present at outputs
I and S, and in the display. The digital input is also taken into account when the empty-tank spectrum
is being recorded (totalizer does not continue). marker 6 in the display indicates that the digital input
is active in the "freeze" function.
NOTE: The function of the digital input is set as standard to "freeze". To switch the function to "hot
start" or to deactivate it completely, the setting will need to be changed in the Service menu of the
BM 70 A/P