Hach sc100, User Manual

Page: 26 / 64

26
Installation
At this time, the manufacturer supports Modbus RS485, Modbus RS232, and Profibus DP
communication protocols. The optional digital output card is installed in the location
indicated in
Figure 22 on page 27 . Terminal block J1 provides user connection to the
optional network card. The terminal connection is based on the selected network card.
Refer to the instructions supplied with the network card for more details.
Note: The sc100/1720E system also supports the AquaTrend Network.
Surge Protection Recommendation for Profibus DP
Many industrial environments are vulnerable to power transients and lightning. Water and
wastewater plants are frequent targets of lightning. Lightning generated fields and power
surges can cause instrument failures at these facilities. Surge protectors limit the
magnitude of over-voltage transients and protect equipment from damage. To be effective
on Data lines, at a minimum, a surge protector should provide two stages of protection
with sub-nanosecond response time. Data line surge protection should be installed on a
Profibus DP network where it might be susceptible to lightning or transients. The purpose
of the surge protector is to protect the equipment that it is located next to, not the
network cable.
For the best performance/protection connect the surge protector as close as possible to
the device to be protected and connect the device (instrument) ground connection through
the surge protector’s ground to the local protective earth ground. Contact your local
Profibus network component supplier for their recommendation as to which surge
protectors may be best for your system.
Figure 21 RS232 Connection to Customer-supplied Computer 9-pin D Subminiature Connector
Table 6 Digital Output Terminal Assignments
Terminal
Number
AquaTrend
Network
1
Modbus RS485
2-wire
Modbus RS485
4-wire
Modbus RS232 Profibus DP
1 Network A D+ RD+ Rx A1– (out)
2 Network B D– RD– No connection B1+ (out)
3 Network A No connection TD+ Tx A2– (in)
4 Network B No connection TD– No connection B2+ (in)
5 No connection Common Common Common Common
6 No connection No connection No connection No connection No connection
7 Shield Shield Shield Shield Shield
1
The AquaTrend Network only applies to sc100/1720E systems
Common 5
9
8
7
6
Not used 4
Rx 3
Tx 2
Not used 1