Contents
MetPak RG User Manual
Last Change
©
Gill Instruments Ltd
12 February, 2013
Page 7
NOTE.
A 15-metre, 6-pair cable (wires stripped at each end) suitable for
RS232/RS422 or SDI-12 communication is available from Gill Instruments (Part
No. 1723-10-053).
Cable Type Data Comms
Wire type:
24AWG
Wire size:
7x32 AWG.
Cable outer diameter:
6-8mm (to match the hub box gland).
For RS422/485 operation the cable should contain twisted pairs screened to match
the application.
Cable Type Rain Gauge
Wire type:
22AWG
Wire size:
7x30 AWG.
The cable should contain a twisted pair screened.
NOTE:
The Rain Gauge supplied with MetPak RG has a 6 Metre cable connected
to it ready to wire into the MetPak RG hub box.
The following table shows an example manufacturers’ reference; other
manufacturers’ equivalents can be used.
Table 2
Recommended Belden cable types
Application
No. of Pairs
Belden Ref.
Rain Gauge Connection
1
8761
SDI-12 or RS485
2
9729
Digital RS232
3
9503
Digital RS422
4
9504
Cable length
The maximum cable length is dependent on the chosen communication method.
The following table shows the maximum cable lengths for the supported
communication protocols at the given baud rates, using the recommended cable. If
any problems of data corruption etc. are experienced, then a slower baud rate
should be used. Alternatively, a higher specification cable can be tried.
Table 3 Maximum cable lengths for supported communication and sensor network
Communication format
Baud rate
Max. cable length
RS232
19200
6.5M
RS422/485
19200
1000M
SDI-12
1200
90M
Digital Switch Input
Not Applicable
Switch contact and cable
resistance to be less than
1k ohm
