CURRENT LOOP INSTALLATION
WIRING CONNECTIONS
It is recommended that shielded (screened) cable be used for serial
communications. This unit meets the EMC specifications using Alpha #2404
cable or equivalent. There are higher grades of shielded cable, such as four
conductor twisted pair, that offer an even higher degree of noise immunity.
When wiring the 20 mA current loop, remove the bottom terminal block
(TBA), located on the rear of the unit. Refer to the numbers listed with the
terminal descriptions below or those located on the label. Install each wire in its
proper location on the terminal block. When all connections are made, replace
the terminal block into its proper location.
SERIAL TERMINAL DESCRIPTIONS
8. PRINT REQ. - The Print Request terminal is pulled low to activate the unit
to transmit data according to the print function selected in Program Module
#7
(Reference Programming Module #7 for more details)
. In order for a
print request function to occur, E1-CON
(TBA #4)
or E2-CON
(TBA #8)
pin must be programmed for print request.
Note: In order to guarantee a
print-out, the programmed E-CON pin must be held low for at least 20
msec. If this time exceeds 800 msec, a second print-out may occur.
9. -20 mA SRC. - 20 mA current source return path for the transmit loop.
Current flows into this pin.
10. SI+ (Serial In+) -
11. SI- (Serial In-) -
The unit receives commands on the SI terminals. They are connected in
series with the transmit or output terminals of the device to be connected.
12. SO+/+20 mA SRC. (Serial Out+) - 20 mA current source for the transmit
loop (internally connected).
13. SO- (Serial Out-) -
The unit transmits the requested data on the SO terminals. They are connected
in series to the receive input of the device to be connected.
Note: The Serial Input terminals must be held in the mark condition (current
flowing) in order for the unit to respond to a Print Request terminal activation.
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