JOHNSON CONTROLS
216
FORM 201.23-NM2
ISSUE DATE: 09/25/2020
SECTION 7 - OPERATION
Remote Current Limit Reset is only possible if the op-
tion is enabled by both the OPTIONS key selection and
in the factory programmable password protected Unit
Setup Mode.
Remote ISN Current Limit Setpoint
The ISN Current Limit Setpoint can be set via the ISN
comms. The control panel will only accept a Current
Limit Setpoint from the ISN if the control panel is in
Remote Control Mode (under the OPTIONS key). If
the control panel is in Local Control Mode, the ISN
setpoint will be ignored. The minimum and maximum
allowable values will be the same as the minimum and
maximum allowable reset values for the Current Limit
Setpoint under the PROGRAM key. If these values are
exceeded, the minimum or maximum value will be
used.
Contact a local Johnson Controls ISN Representative
for details on ISN controls and capabilities.
Remote Current Limit Reset
The Current Limit Setpoint can be set or reset via the
Remote Current Limit analog input. A zero signal in-
put (0% input) equates to the maximum current limit
setpoint as defined under the PROGRAM key Cur-
rent Limit Setpoint. A full scale signal input (100%
input) equates to the minimum current limit setpoint
as defined under the PROGRAM key Current Limit
Setpoint. The current limit value is linear and may be
adjusted anywhere between the maximum and mini-
mum points of 0% (no offset) and 100% (max. current
limiting).
This input may be used either in Local or Remote Con-
trol Mode. This input will be ignored if the Remote
Current Limit is disabled under the OPTIONS key.
Once a change to the input is registered, a timer is set
to the value of the Remote Inputs Service Time as pro-
grammable under the Unit Setup Mode at the factory
for the default value of 15 minutes. The low limit is 5
minutes and the high limit is 60 minutes. The Remote
input will be ignored until this timer expires. The tim-
er assures that rapid changes in a remote reset signal
don’t result in poor temperature control or excessive
compressor cycling. In most instances, this timer will
not need to be changed, since reset more often than 15
minutes will create problems with chilled liquid tem-
perature control. Factory Service should be contacted
if a timer change is required.
Control board jumper JP5 must be positioned correctly
to receive either a voltage (0 VDC to 10 VDC or 2
VDC to 10 VDC) or current (0 mA to 20 mA or 4 mA
to 20 mA) signal. Place the jumper in the “V” position
for a voltage signal or mA for a current signal (See Fig-
ure 27 on page 166 and Figure 28 on page 167). The
software must be configured under the OPTIONS key
for the type of input signal to be used.
The minimum current limit setpoint is achieved at ei-
ther 10 VDC or 20 mA. Sending the minimum signal
(0 VDC, 2 VDC, 0 mA, or 4 mA based on the OP-
TIONS key setting) causes the current limit to revert
back to its maximum value.
0 VDC through Reset Input
A 0 VDC signal sets the current limit to the maximum
value. A 10 VDC signal sets the current limit to the
minimum value. The current limit is ramped linearly
between these limits as the input varies between 0
VDC and 10 VDC. In order for this input to work prop-
erly, the Remote Current Limit must be programmed
for 0 VDC through 10 VDC input (OPTIONS key) and
Chiller Control Board jumper JP5 placed in the “V”
position.
2 VDC through 10 VDC Reset Input
A 0 VDC to 2 VDC signal sets the current limit to the
maximum value. A 10 VDC signal sets the current limit
to the minimum value. The current limit is ramped lin-
early between these limits as the input varies between 2
VDC and 10 VDC. In order for this input to work prop-
erly, the Remote Current Limit must be programmed
for 2 VDC through 10 VDC input (OPTIONS key) and
Chiller Control Board jumper JP5 placed in the “V”
position.
0 mA through 20 mA Reset Input
A 0 mA signal sets the current limit to the maximum
value. A 20 mA signal sets the current limit to the mini-
mum value. The current limit is ramped linearly be-
tween these limits as the input varies between 0 mA
and 20 mA. In order for this input to work properly, the
Remote Current Limit must be programmed for 0 mA
through 20 mA input (OPTIONS key) and Chiller Con-
trol Board jumper JP5 placed in the “mA” position.
4 mA through 20 mA Reset Input
A 4 mA signal sets the current limit to the maximum
value. A 20 mA signal sets the current limit to the mini-
mum value. The current limit is ramped linearly be-
tween these limits as the input varies between 4 mA
and 20 mA. In order for this input to work properly, the
Remote Current Limit must be programmed for 4 mA
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