Heinrichs Messtechnik GmbH
Page 28 of 118
OPERATING MANUAL TMU-W / UMC4
Current outputs
4.8.2.1
Accuracy
Maximal error of the current outputs is ±0.1 % of the actual r 0.05 % full scale flow.
4.8.2.2
Load
Standard version:
500 ohms
Explosion-proof version:
500 ohms
HART
minimum load:
250 ohms
The minimal voltage required at the passive current output terminals to ensure correct operation is 10 V.
The maximum voltage of 30 V must never be exceeded.
The maximum load is dependent on the applied terminal voltage and can be calculated using the following
equation:
500
23
1
10
max
mA
V
U
R
0 Ohm
100 Ohm
200 Ohm
300 Ohm
400 Ohm
500 Ohm
600 Ohm
0 V
5 V
10 V
15 V
20 V
25 V
30 V
load
external power supply voltage
maximum load
Rmax
Figure 1: Maximum Loads of the Current Outputs
4.8.2.3
HART®
A number of connection possibilities are available for HART
®
communication, with the condition that the
loop resistance is less than the maximum load specified in Section 4.8.2, “Current outputs” on page 28. The
HART
®
interface is connected via terminal 11 and 12 or 41 and 42 respectively. The minimum load
impedance of 250 Ω must be adhered to.
For information regarding operation of the transmitter using the HART
hand-held terminal, see “Operation
of the UMC4 transmitter using the HART
hand-held terminal.”
