On Jun 1, 15:59, wai-sun chia wrote: itself? This is for a DZ11-A/B/E, M7819. The 20mA versions (DZ11-C/D/F, M7814) are different. The information isn't in either the User Manual or the Technical Manual, so I resorted to reading circuit diagrams from the module assembly microfiche. It's not very clear in parts, but the pinout is: Chan. TxD RxD SG DTR DCD RI 0 19 21 22 1 2 20 1 23 25 26 3 4 24 2 27 29 30 5 6 28 3 31 33 34 7 8 32 4 35 37 38 9 10 36 5 39 41 42 11 12 40 6 43 45 46 13 14 44 7 47 49 50 15 16 48 Pins 17 and 18 are also ground. On the DB25 end, TxD is pin 2, RxD is pin 3, SG is pin 7, DTR is pin 20, DCD is pin 8, RI is pin 22. -- Pete Peter Turnbull Network Manager University of York