Dwyer 8600 - Manual (Page 18)

949-1277-3 Page 18 December, 1998
Option 992, 993, Serial Communication.
The serial communications options allow the control to be written to and read
from a remote computer or other similay digital device. Communication is
allowed either through a RS-485 (Option 992) port, or a RS-232 (Option 993)
port.
Wire the communication lines as shown on Page 7. 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 Addr and
bAUd menu items in the Secure Menu. THE BAUD RATE AND ADDRESS
MENU ITEMS WILL TAKE EFFECT ON THE NEXT POWER UP OF THE
CONTROL. BE SURE TO POWER CYCLE THE CONTROL BEFORE
USING THE NEW BAUD RATE AND ADDRESS.
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 LOrE
menu item in the Secondary Menu to LOC. To allow the host to write
commands to the control set LOrE to rE. (The host does have the ability to
change the LOrE 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 (nAt) to monitor the addressing of the
control. When the LOrE is set to rE and the nAt is set to any value other than
Off, 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 nAt, then the control will display
the error message CHEC LOrE. To clear the message set LOrE to LOC.
MENU SELECTIONS
PRIMARY MENU
Press INDEX to advance to the next menu item. Press UP ARROW or
DOWN ARROW to change the value in the display. Press ENTER to retain
the value. If StAt (Secondary Menu) is On, the three program status menu
items will precede the following.
#SP1 (Option 948, 4-Stage Set Point) or
SP1 Set Point 1 Adjust, Control Point 1.
SP2 Set Point 2 Adjust (if equipped), Control Point 2.