MT5634ZBA-GLOBAL Multi-Tech Systems, MT5634ZBA-GLOBAL Datasheet - Page 55

• Manufacturer Part Number: MT5634ZBA-GLOBAL
• Description: MODEM V.90 DATA/FAX GLOBAL
• Manufacturer: Multi-Tech Systems
• Series: MultiModem® ZBAr

Specifications of MT5634ZBA-GLOBAL

• Data Format: V.90
• Mounting Type: Desktop
• Package / Case: 5.7" L x 4.3" W x 1.0" H (145mm x 109mm x 25mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -
• Interface: -
• Other names: 881-1149; MT5634ZBA-GLOBAL

Interface Configuration Commands
The commands in this section are used to define the interface between the PC and the modem.
+VBT
Description:
Syntax:
Values:
Reports:
Example:
Result Codes:
Multi-Tech Systems, Inc. AT Commands for the MultiModem & SocketModem MT9234 Series (S000434H)
Set Modem Flow Control Assert and Deassert Points
The +VBT= command is used to set the flow control assert and deassert points
inside the modem's internal transmit buffer. As data is sent from the PC to the
modem and is stored in the modem's buffer, when the number of octets in the buffer
equals the <assert> value, the modem asserts flow control to the PC (e.g., turns off
CTS circuits, or sends an XOFF character). As the modem removes data from the
buffer and processes the data, when the number of octets in the buffer equals the
<deassert> value, the modem de-asserts flow control (e.g., turns on CTS circuits, or
sends an XON character). The modem may inform the PC (using the +VBT=?
command) that the PC does not permit the modifying of the flow control assert and
deassert points by returning a single value, not in the range of values, for each
control point.
The +VBT= command controls the amount of "skid" in the modem's voice buffer,
where "skid" is the amount of octets that the modem could accept before losing data
after the modem asserts an off flow control signal to the PC.
You can use the +VBT= command to balance performance versus robustness. For
example, if the PC knows there are only 16450 UARTs present, a small "skid" is
probably sufficient. If there are 16550 UARTs present, a larger "skid" is probably
required.
AT+VBT=<deassert>,<assert>
<assert> and <deassert> are buffer offsets from the start of the buffer. The buffer's
first position is 0. The offset units are octets.
+VBT?
+VBT=?
In the lines below, the +VBT=? command is used to ask about the modem's flow
control and buffer size ranges. The modem reports the deassert point is adjustable
between 20 and 100 octets, the assert point is adjustable between 150 and 180
octets, and the transmit buffer size is 200 octets.
OK if the modem accepts the command
ERROR if either the <assert> or <deassert> parameter is greater than the buffer size,
or if the <de-assert> parameter is greater than or equal to the <assert> value.
Displays current or selected values.
Displays the possible <assert> and <deassert> values set by the +VBT=
command, followed by the OK result code.
AT+VBT=?
(20-100) , (150-180) , (200)
OK
Chapter 4 – Voice Commands
55