Ascon ALS-3-232 Adapter

INSTRUMENTS WITH AN RS-485 INTERFACE (2 WIRE)
The hardware must be RS-485 compatible.
The line must be made up of a twisted cable with a characteristic impedance
of about 120 W. On the power supply board of the instruments of the "Q" series, there are three jumpers, S1, S2 and S3, with 2 positions that have the
following functions:
Jumper S1 S2 S3
Function of pos. 1 None None None
Function of pos. 2 120 ½ termination Polarization 1 Polarization 1
The standard positions of the switches are indicated in grey.
The S1 pos. 2 termination function is strongly recommended for the two devices located at the two ends of the line, as shown in the following basic diagram:
Host
DEVICE 1
DEVICE 2
DEVICE "n"
Rt
Rt
Signal ground Rg
Rg G/R
Note 1.
G/R
Rg G/R
Rg G/R
The two-wire transception line can be polarized using jumpers S2 and S3.
The polarization must only be carried out on 1 device on the line and both
jumpers must be set to position 2.
G = Generatore R = Ricevitore G/R = Combinazione Generatore Ricevitore Rt
= Resistenza di terminazione: un driver può pilotare 32 ricevitori più 2
resistenze da 120 ½.
Rg = Resistenza da 100 ½.
6.4.1
REFERENCES
Gould Modbus Protocol Reference Guide (PI-MBUS300 Rev. B) APRIL
JBUS Specification
GLOBAL ENG. DOC. EIA STANARD RS -485 GOULD
29
General description
6.4