12.4 4-20 mA Remote Signal
Jumper JP on the I/O board must be set to 20 mA.
To calculate the chilled liquid setpoint for values
between 4 mA and 20 mA use the following formula:
Setpoint = Local Chilled Liquid Se °C Reset
°C Reset = ((mA signal - 4) x *Max Reset Value)
16
Example:
Local Chilled Liquid Setpoint = 6.4 °C
*Max Reset Value = 6.0 °C
Input Signal = 8 mA
°C Reset = ((8mA - 4mA) x 6.0 °C) = 1.5 °C Reset
16
Setpoint = 6.4 °C + 1.5 °C = 7.9 °C
* Max Reset Value is the 'Max EMS-PWM Remote
Temp. Reset' setpoint value described in the
programming section under Cooling Setpoints.
Programmable values are from 1.11 °C to 11.11°C).
12.5 EMS-PWM Remote Temperature Reset
The EMS-PWM feature is not normally
available. If the message REMOTE TEMP
RESET INPUT (being the analogue input) is
visible under the OPTION key even when set
to DISABLED the EMS-PWM feature is
disabled. Contact Johnson Controls York
Product service if you require this feature. If
enabled this feature will work even when the
Option Local/Remote mode is set to Local.
This input is not active if an ISN, Bacnet or
Modbus is connected, Option Local/Remote
is set to Remote and the ISN is not handing
back control to the panel by sending 99 on ISN
page 03.
The EMS-PWM remote temperature reset value at
terminals 13 - 20 on -XTBC1, will reset the chilled liquid
'SETPOINT' based on the length of time the contacts
remain closed. The maximum temperature reset
allowed is achieved with a contact closure of 11
seconds. One second is the shortest time allowed and
causes the chilled liquid 'SETPOINT' to revert back to
the local programmed value.
The reset value is always added to the chilled liquid
'SETPOINT', meaning that this function never lowers
the chilled liquid 'SETPOINT' below the locally
programmed value, it can only reset to a higher value.
The microprocessor board must be refreshed between
30 seconds and 30 minutes. Any contact closure
occurring sooner than 30 seconds will be ignored. If
more than 30 minutes elapse before the next contact
closure, the setpoint will revert back to the locally
programmed value.
The new chilled liquid 'SETPOINT' is calculated:
'SETPOINT' = chilled liquid 'SETPOINT' + °'RESET'
°'RESET' = (Contact Closure - 1) x (*Max. Reset Value)
10
Example:
Local Chilled Liquid Setpoint = 6.1°C.
*Max Reset Value = 10.0°C
Contact Closure Time = 6 Seconds.
(6 sec - 1) * (10.0°C/10) = 5.0°C
Reset 'SETPOINT' = 6.1°C + 5.0°C = 11.1°C
This can be viewed by pressing the 'SETPOINTS' key
twice:
1
-
39
Form 201.26.OI1(11/09)
R E M
S E T P
=
1 1 . 1 ° C
R A N G E
=
+ / - 1 . 1 ° C
