Ametek Sorensen Asterion DC Series, Operation Manual

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Asterion DC Series Calibration
M330460-01 Rev D 3-49
3.4
Remote Current Programming
Remote current programming can be summed with the front panel or digital setting;
see Section 3.3. Remote current programming is used for applications that require
the output current be programmed (controlled) from a remote instrument. An external
resistance or external voltage source or external 4-20mA source may be used as a
programming device. When using remote current programming, a shielded, twisted-
pair cable is recommended to prevent noise interference to programming signals.
3.4.1 Remote Current Programming by Resistance
Analog Reference source is selected as Resistance from the front Panel. Refer to
Figure 3-101. The resistance-programming default coefficient for output current is
(100% rated output current) / 5
kΩ, with input at Pin 20 (IPRG_ISOUR) and return to
Pin 18 (RTN_PRG). An internal current source, factory-set at 1 mA, from Pin 20 is
utilized to drive the resistance. This produces a transfer function for output current,
as follows:
I
out
= * 1 % rated output urrent / 5 kΩ , with in kΩ
Full Scale current programming resistance can be modified from default 5
kΩ to any
other value, from 2
kΩ to 10 kΩ. Refer to Section 3.1.8.4. Then the transfer function
for output current, as follows:
I
out
= * 1 % rated output urrent / FSC kΩ , with in kΩ.
If multiple switches or relays are used to select resistors to program different
current levels, make-before-break contacts are recommended since an open
circuit (or resistance greater than what you have selected as the maximum
resistance value (2k to 10k ohms) 10k ohms) will set the output to the full
current your model can produce.
An open circuit between remote programming pins while in remote programming
mode will output the full current value that your model is rated to produce. A short
must be placed between these pins will set an output a value of zero.