User`s manual

4-8 Intellio C320Turbo/PCI User's Manual
Syntax for UNIX SVR4
#include <sys/stropts.h>
#include <sys/sysmacros.h>
#define MTCDTR 0x404
#define TurnON 1
#define TurnOFF 0
struct strioctl ioc;
int setting;
setting = TurnON /* or TurnOFF */;
ioc.ic_cmd = MTCDTR;
ioc.ic_timout = 0;
ioc.ic_len = sizeof(int);
ioc.ic_dp = (char *)&setting;
ioctl(moxa_fd, I_STR, &ioc);
5. MLOWATER
Sometimes the application software may not be able to write any further data to the
output buffer because of the output buffer being full. The application has to wait
until the output buffer has 'enough space' again. The criteria to tell if the output
buffer has 'enough space' is that whether the output buffer reached its 'low water'
level. That is the output buffer will accept further data only when the 'low water'
level is reached.
If the 'low water' value is relatively small, you may find that the output buffer
become empty before you write another block of data (this is quite possible because
UNIX is time-sharing multitasking environment). This will result in discontinuous
data transmission. In a timeout-sensitive application, e.g. facsimile (FAX)
transmission, discontinuous data may falter the operation.
The default 'low water' is 512 bytes. You can enlarge it but better not exceed one half
of the output buffer. Each port’s output buffer depends on the number of total ports.
See below.
Model Output buffer/each port
C320Turbo/PCI w/8 ports 32K bytes
C320Turbo/PCI w/16ports 16K bytes
C320Turbo/PCI w/24ports 8K bytes
C320Turbo/PCI w/32ports 4K bytes