ABB SM500F User Manual

SM500F
Field mountable paperless recorder 2 Installation
22 IM/SM500F Rev. Z
2.9.1 Host Computer Serial Communications
The serial interface option module has been designed to operate using the Modbus Remote Terminal Unit
(RTU) Master/Slave protocol. An appropriate RS422/485 communications driver must fitted to the host
(Master) computer. It is strongly recommended that the interface has galvanic isolation to protect the
computer from lightning damage and to increase signal immunity to noise pick-up.
2.9.2 Two-wire Connection
Modbus serial communications must be configured as two-wire serial links – see Fig. 2.14. The instrument
must be added to the link configuration on the host system – refer to information supplied with the host
system.
Fig. 2.14 Two-wire Connection
1
2
3
4
5
6
Ter m in al B lo ck F
Host Computer
Rx/Tx +
Rx/Tx –
COM
GND
1.8 k Pull-up
Resistor
1.8 k Pull-down
Resistor
Tx +
Tx –
Rx +
Rx –
0 V
+5 V
'B'
'B'
'A'
'A'
GND

ABB SM500F Specifications

General

Brand	ABB
Model	SM500F
Category	Measuring Instruments
Language	English