May, 2013
Page 21 of 52
949-1194 Rev. 7
Option 948, 4-Stage Set Point.
The 4-stage set point option allows four different values to be used for
S P 1
and all of the
values associated with the
t u n E
menu items. The control will switch to a given stage when
an external contact or contacts are made or opened across the appropriate terminals at
the rear of the control (
S P S A
, Set Point Switch Action, set for remote,
r E
), or when the
stage is selected from the Secondary Menu,
S P
(when
S P S A
is set for
I n t
). When the state
of a contact changes (or the stage number is changed in the Secondary Menu), the values
in use are stored and the previously stored values for the new stage are used.
Wire the input as shown on page 10.
Usually the control is configured for external switching of the stages. In this case, the
operation is usually automatic, selected by the external switches driven by the machine
logic. If it is necessary to program the stages in advance, you may select the stage to
modify with the
S P
menu item. When
S P
is changed while the
S P S A
is set for
r E
, the
selected stage is displayed for modification, but only used when the appropriate contact is
made.
Option 992, 993, 995, 996 Serial Communication.
The serial communications options allow the control to be written to and read from a
remote computer or other similar digital device. Communication is allowed either through a
RS-485 (Option 992, 996) port, or a RS-232 (Option 993, 995) port.
Wire the communication lines as shown on Page 11. Wiring for the RS-485 is run from
control to control in a daisy chain fashion with a termination resistor (120 ohms) across the
transmit and receive terminals of the last control in the chain.
Select the control address and communication baud rate with the
A d d r
and
b A U d
menu
items in the Secure Menu.
NOTE:
THE BAUD RATE AND ADDRESS MENU ITEM SETTINGS WILL TAKE EFFECT
ON THE NEXT POWER UP OF THE CONTROL. BE SURE TO TURN THE POWER TO
THE CONTROL OFF AND ON BEFORE USING THE NEW BAUD RATE AND ADDRESS
VALUES.
In operation, you have the option of preventing a write command from the host computer.
To prevent the host from writing to the control change the
L O r E
menu item in the
Secondary Menu to
L O C
. To allow the host to write commands to the control set
L O r E
to
r E
. (The host does have the ability to change the
L O r E
state, but it is not automatic.)
If your system depends on constant reading or writing to and from the host, you may wish
to set the No Activity Timer (
n A t
) to monitor the addressing of the control. When the
L O r E
is set to
r E
and the
n A t
is set to any value other than
O F F
, the control will expect to be
addressed on a regular basis. If the control is not addressed in the time set by the value of
n A t
, then the control will display the error message
C H E C L O r E
. To clear the message
set
L O r E
to
L O C
.
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.com
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