Intermec EasyCoder 501 E Installation & Operation Manual page 143

Appendix 4 Interfaces
Standard Interface "uart1:", cont.
20 mA Current Loop
142
The 20 mA current loop interface is a single-ended, full duplex
serial interface which uses current instead of voltage to transmit
signals on a four-wire line. 20 mA current corresponds to a logical
"0" and 0 mA corresponds to a logical "1".
Optocouplers are used to separate the transmission line from the
internal logics of the printer and the host computer. Therefore
this interface is suitable where electrical interference may occur,
and for transmission over longer distances (up to 500 metres or
1,500 ft.).
Depending on the confi guration of the connection cable between
printer and host computer, the printer can work either active (that
is, supplying the current) or passive. A transmission speed between
300 and 9,600 baud is recommended.
- +
P203
P202
IC-205
IC-206
Intermec EasyCoder 501 E – Installation & Operation Ed. 1
P-203 (external +5 VDC)
P-202 (interface select)
232
CL
422
IC-205 & IC-206 (optocouplers)