A.3 Limiting And Operating Data Of The Cl Data Interface - Mettler Toledo AE Série Mode D'emploi

The connection cable must meet the following requirements:
– 4-wire, two twisted pairs
– shielded
– resistance approx. 125 Ω/km
– cable cross section (per conductor) 0.14 mm
– capacitance approx. 130 nF/km
– maximum admissible cable length up to 1200 baud: 1000 meters
A .3 Limiting and operating data of the CL Data Interface
To assure that transfer will be free of disturbance, the following conditions must also be met:
– Voltage level of the source: 15 V (+10 %/-0 %)
– Current (HIGH) between 18...24 mA
– Slope 2. . .20 mA/µs
– Cables defined above
4
2
2400 baud or more: 500 meters
Transfer principle:
Limiting data:
Both transfer loops must be powered by an external current source.
To prevent the balance CL data interface from being destroyed by
an external current source, it is absolutely necessary that the limiting
data given in the adjacent diagram be observed:
The U/l characteristics of the sources must be within the
crosshatched area.
– Transfer loop (current level)
HIGH: see limiting data
LOW: less than 1 mA
– Receive loop (response thereshold)
HIGH: more than 15 mA
LOW: less than 5 mA
Both loops are protected against damage caused by incorrect
polartity of the current sources.
– full duplex with no automatic echo
– bit serial
– asynchronous
– one start and one stop bit
– 20 mA loop current (current in idle
condition)
– 7 bits per character plus parity bit (ASCII)
– handshake accomplished