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1.3.9
RS485 Se rial Com mu ni ca tions (Op tion)
The connections for the three-wire RS485 serial communications option (if fitted) are on
Terminals 16, 17 and 18, as shown in Figure 1-4. Where several instruments are
connected to one master port, the master port transceiver in the active state should be
capable of driving a load of 12k
Ω
per instrument; the master port transceiver in the
passive state must have pull-up/pull-down resistors of sufficiently low impedance to
ensure that it remains in the quiescent state whilst supplying up to
±
100
µ
A each to the
instrument’s transceivers in the high impedance state.
1-8
November, 2000
SM067-1
Sec tion 1
1
8
-DIN Digi tal In di ca tor
59039
In stal la tion
Prod uct Man ual - Vol ume II