Hach-Lange SC 60 - Manual (Page 28)

24
Installation
terminal connection is based on the selected network card. Refer to
the instructions supplied with the network card for more details.
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 the equipment
from damage. For 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 best performance/protection connect the surge protector as
close as possible to the device. Connect the device ground
connection through the surge protector ground to the local
protective earth ground. Contact the local Profibus network
component supplier for recommendations on the best surge
protector for a system.
Table 6: Digital Output Terminal Assignments
Terminal Number Modbus RS485 2-wire Modbus RS485 4-wire Modbus RS232 Profibus DP
1 D+ RD+ Rx A1– (out)
2 D– RD– No connection B1+ (out)
3 No connection TD+ Tx A2– (in)
4 No connection TD– No connection B2+ (in)
5 Common Common Common Common
6 No connection No connection No connection No connection
7 Shield Shield Shield Shield
Figure 20 RS232 Connection to Customer-supplied Computer 9-pin D Subminiature Connector
Common 5
9
8
7
6
Not used 4
Rx 3
Tx 2
Not used 1