Eia-422/485 Communications Card Wiring; Figure 4-8. Eia-422 Wiring Schematic; Figure 4-9. Eia-485 Wiring Schematic - Emerson Fisher FLOBOSS 407 Instruction Manual

FloBoss 407 Instruction Manual

4.4.2 EIA-422/485 Communications Card Wiring

Figure 4-8 shows the relationship between the EIA-422 signals and terminal numbers for the COM2
terminal block. EIA-422 wiring should be twisted pair cable, one pair for transmitting and one pair for
receiving. Jumper P4 in the newer card (Jumper P3 in the older card) is used to control the RTS
transmit function in the EIA-422 mode. This jumper has a default setting of RTS for multi-drop
communications. Placing this jumper in the ON position enables the card to continuously transmit
(such as for point-to-point). This jumper has no effect when the card is wired for EIA-485 operation.
EIA-422/485 CARD
RXD
RTS
TXD
P4/P3 RTS
ON
+5V
Figure 4-9 shows the relationship between the EIA-485 signals and terminal numbers for the COM2
terminal block. Wiring should be twisted-pair cable. On newer design cards, Jumper P3 can be set to
apply (LD) or remove (N/L) a 140-ohm load. Typically, the load would be used in a point-to-point
application, and removed in multi-drop applications, except for one device on each end of the bus.
EIA-422/485 CARD
RXD
RTS
TXD
Note: Jumper P3 is used for loading only on newer card.
Rev 5/00
R
DIR
D
R
DIR
D

Figure 4-8. EIA-422 Wiring Schematic

LD
R
DIR
N/L
140
P3
D

Figure 4-9. EIA-485 Wiring Schematic

P2
-RXD
21
+RXD
19
-TXD
24
+TXD
17
23
18
20
22
COM
15
RXD
21
TXD
19
24
17
23
18
20
22
COM
15
COM2
TERMINAL
EIA-422
BLOCK
3 -RECEIVE
5 +RECEIVE
2 -TRANSMIT
7 +TRANSMIT
1
8
6
4
9
DOC0212T
Mod051000
COM2
TERMINAL
EIA-485
BLOCK
3 -OUT
5 +OUT
9
DOC0213A
Mod051000
4-13