VortexMaster FSV430, FSV450 SwirlMaster FSS430, FSS450 | CI/FSV/FSS/430/450-EN  Rev. G  33 
 
Cable specification 
The maximum permissible length depends on the baud rate, 
the cable (diameter, capacity and surge impedance), the 
number of loads in the device chain, and the network 
configuration (2-core or 4-core). 
—  At a baud rate of 9600 and with a conductor cross section 
of at least 0.14 mm
2
 (AWG 26), the maximum length is 
1000 m (3280 ft). 
—  If a 4-core cable is used in a 2-wire system, the maximum 
length must be halved. 
—  The spur lines must be short (maximum of 20 m [66 ft]).  
—  When using a distributor with "n" connections, the 
maximum length of each branch is calculated as follows: 
40 m (131 ft) divided by "n". 
 
The maximum cable length depends on the type of cable 
used. The following standard values apply: 
—  Up to 6 m (20 ft): cable with standard shielding or twisted-
pair cable. 
—  Up to 300 m (984 ft): double twisted-pair cable with 
overall foil shielding and integrated earth cable. 
—  Up to 1200 m (3937 ft): double twisted-pair cable with 
individual foil shielding and integrated earth cables. 
Example: Belden 9729 or equivalent cable. 
 
A category 5 cable can be used for Modbus RS485 up to a 
maximum length of 600 m (1968 ft). For the symmetrical pairs 
in RS485 systems, a surge impedance of more than 100 Ω is 
preferred, especially at a baud rate of 19,200 and above. 
 
 
 
5.6.6  Electrical data for inputs and outputs 
Power supply 
 
Devices with HART communication 
Terminals  PWR/COMM + / PWR/COMM – 
Supply voltage  12 ... 42 V DC 
Residual ripple  Maximum 5 % or Uss = ±1.5 V 
Power consumption  < 1 W 
 
Devices with Modbus communication 
Terminals  PWR + / PWR – 
Supply voltage  9 ... 30 V DC 
Residual ripple  Maximum 5 % or Uss = ±1.5 V 
Power consumption  < 1 W 
 
Uss  Peak-to-peak value of voltage 
 
Current output / HART output 
Only for devices with HART communication. 
 
Fig. 36:  Load diagram of current output; load depending on supply 
voltage 
 
Terminals: PWR/COMM + / PWR/COMM – 
 
In HART communication, the smallest load is R
B
 = 250 Ω. 
The load R
B
 is calculated as a function of the available supply 
voltage U
S
 and the selected signal current I
B
 as follows: 
 
R
B S 
= U
B
/ I 
R
B
 Load resistance 
U
S
 Supply voltage 
I
B
 Signalstrom 
 
G11769
1,6
1,4
1,2
1,0
0,8
0,6
0,4
0,2
0