3 - 2                         3 - 2 
MELSEC-Q
3   SPECIFICATIONS 
 
 
 
 
 
 3 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Specification 
Item 
QD51 QD51-R24 
Console  PC/AT personal computer. 
Multitask debugging  Possible (when the debugger is used) 
RS-232  1 : 1 
Line configuration (
3
) 
RS-422/485 
 
1 : 1, 1 : n, n : 1, m : n 
RS-232  Max. 15 m Transmission distance 
(Total cable length) 
RS-422/485 
 
Max. 1200 m (Total cable length) 
Number of writes to flash ROM  Maximum 100,000 times to the same area. 
Number of occupied I/O points 
32 points per slot (I/O assignment: Intelli: 32 points) (
4
) 
RS-232 
7/0.127 
 P HRV-SV External diameter 8.5 mm or greater (Manufactured by 
Oki Electric Wire (Corp.)  The number of pairs is shown in the 
 part) 
Recommended cables 
RS-422/485 
SPEV (SB) –MPC-0.2 
 3P External diameter  approx. 6.5 mm 
(Manufactured by Mitsubishi Electric Wire Co. Ltd.) 
SPEV (SB) -0.2 
 3P External diameter  approx. 7.5 mm (Manufactured by 
Mitsubishi Electric Wire Co. Ltd.) (
5
) 
5 V DC internal current consumption   0.26A  0.31A 
External dimensions  98 (3.86 in.) (H)   27.4 (1.08 in.) (W)   90 (3.54 in.) (D) [mm] 
Weight   0.20kg (0.44lb) 
 
3 This shows combinations when the external device(s) and programmable 
controller CPU(s) are connected. (External device side : Programmable 
controller CPU side) The value, n or the total of m + n becomes a maximum 
of 32. 
4 To use the QD51(-R24), switch settings must be configured by GX Developer. 
Refer to Section 5.6 for the switch settings of GX Developer. 
5 The electrical characteristics of the recommended cables SPEV (SB) –MPC-
0.2 
 3P and SPEV (SB) -0.2   3P are equivalent, however, their external 
dimensions and internal wire colors are different each other.