Intek RheoVac 940 User Manual
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TABLE II. RJ-1 1 to DB-9 Module Adapter
RS-232 CONFIGURATION
RS-422 CONFIGURATION
RJ-11 Pin Out
DB-9 Pin Out
RJ-11 Pin Out
DB-9 Pin Out
1
Tx (tra nsmit)
1
N/C
1
Tx+ (transmit+)
1
Rx! (receive!)
2
N/C
2
Tx (tra nsmit)
2
Tx! (transmit!)
2
Rx+ (receive+)
3
Rx (receive)
3
Rx (receive)
3
Rx+ (receive+)
3
Tx+ (transmit+)
4
N/C
4
N/C
4
Rx! (receive!)
4
N/C
5
Power (+5V)
5
Ground
5
Power (+5V)
5
Ground
6
Ground
6
Pulled high
6
Ground
6
Tx! (transmit!)
7
N/C
7
TBD
8
Pulled high
8
TBD
9
N/C
9
TBD
2.6 RheoVac SYSTEM GROUNDING
The RheoVac electrical system includes the RheoVac monitor and your data collecting inputs. In
general, it is good practice to use a single point grounding scheme to terminate the system output circuit
to a stable reference potential. Improper grounding may cause significant data noise, or in extreme cases,
damage your equipment. To simplify this task, determine which outputs you will be using and refer to
the following section for specific grounding instructions.
•
RS232/422 Serial Output Only - Many PCs have non-isolated serial ports. You must
determine if your serial port is isolated. With your PC (or DCS, etc.) powered and plugged
into a grounded outlet measure both the Vdc and Vac between the local circuit’s earth ground
and pin 5 of the PC’s RS232 DB-9 connector. If the voltage is not zero the circuit needs to
be grounded. Connect a locally earth-grounded wire to the RheoVac instrument’s “OUT1”
(
!
) terminal of JP7 located next to the RS232/422 jack (see Figure 9). If the voltage reads
zero, no additional grounding should be attached. Additionally, we have seen noise
problems with certain laptop computers when they are connected to their external power
supplies. Some of them are not fully isolated and have signal noise levels as high as 12Vac
on the serial port GND pin. In this case, the circuit should also be grounded by connecting
a wire to the RheoVac’s “OUT1” (
!
) terminal.
•
4-20mA Output Only - If only a single output channel is used, it may be connected directly
to a non-isolated input channel without any additional grounding. Any additional output
connections require isolated inputs. If all inputs are isolated, regardless of how many are
used, a single channel should be grounded locally near the input card(s). In this case, connect
a locally earth-grounded wire to one of the 4-20mA (
!
) terminals.
•
Multiple Outputs - Review the special wiring configurations above. Connecting all of the
used outputs to isolated input devices results in one common isolated circuit. This common
circuit needs to be grounded at a single point. Choose one of the ground points listed above.