GTCO MM II 1201 - Users Guide - Manual (Page 11)

MM II 11
The interface accommodates RS-232C and TTL. (Do not use both at the same time.)
RS-232C – CITTL Interface: 25-Pin D Connector Pin Assignments
Pin Wire Name Description
1
2
3
7
9
11 GND
TXD
RXD
signal ground
+12 VDC
TXD Protective, frame ground
Transmits data to host (RS-232C only)
Receives data from host (RS-232C or TTL)
Return for data
Power to tablet from host
Transmits data to host (TTL only)
Pin 9 is for powering the tablet from the host. The host must supply a +12 VDC at 250 mA,
less than 50 mV ripple, +/-10% regulation and a rise time less than 100 milliseconds.
CAUTION:
 Never power the tablet from the power supply and host simultaneously.
 Pin 9 and the power supply socket are connected inside the 25-pin D connector.
Therefore, power applied to one, also exists on the other. Ensure that nothing is
attached to the source not in use.
RS-232C Interface
The RS-232C lines are configured as DTE (Data Terminal Equipment). The signal levels
comply with standard signal levels for data transmission:
RS-232C Signal Levels
RS-232C Interface Interchange Voltage
-3V to -12V +3V to +12V
Binary states
Signal condition 1
Mark 0
Space
NOTE: The source is the EIA Standard RS-232C: Interface between Data Terminal
Equipment and Data Communication Equipment Employing Serial Binary Data
Interchange, by the Engineering Department of the Electronic Industries Association
(Washington, D.C.: EIA, 1969).